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Need Math Help?

Chaco

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May 21, 2008
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NC
I need help with a bit of Geometry alt, I really don't remember this stuff. And before you say that's easy. I'm 15. So...HA!

A(7,7) B(4,-2) C(0,6)

-Use the coordinates of Triangle ABC to find the following.
-Equations should be written in slope-intercept form (y=mx+b) and standard form (Ax+By=C)

Find the three altitude equations:

from A:
from B:
from C:



Thanks in advance.
 

AltF4

BRoomer
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What you're going to have to do is first find the equations of each line in point slope form, and then convert it to Y-intercept form.

So all you need is a point on the line and the slope of the line. The points are easy. They're given to you. In order to find the slopes, use the opposite line. You know that the altitude is perpendicular to the opposite line. So just find the slope of the opposite line, and take the negative reciprocal of it.

Then do that three times.
 

Proud_Smash_N00b

Smash Ace
Joined
Jul 4, 2007
Messages
873
Location
La Mirada, California
I need advice on finding limits. After putting it away for a few weeks, I feel stumped going back into it. It's like each equation ends up with 0/0 when x is plugged in but 99.9% of the time, it is some other number instead of not having a limit. It's like the only time there is no limit is when lim 1/x when x->0 and stuff like that.

For example, the limit of (cos x)-1/x as x approaches 0 is 0 but when you plug in x, it ends up as 0/0 but the limit is actually zero. I just don't get how that happens.

When finding limits, do you have to like use some theorem that doesn't make it infinity by any means necessary? If the limit of some function is infinity at some point, that means that there is no limit right?

Btw, is there a special limit formula for the limit of ln equations?

Thanks in advance
 

AltF4

BRoomer
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Smash Noob:

When you get a 0/0 in a function, that means you have a "removable discontinuity" in the derivative function. Essentially that means there's a little missing hole where the derivative is.

Like if you have the function f'(x) = (x-1)(x+2) / (x+2).

You can see, that at x = -2, you'll get 0/0. But it's "removable" because you can just cancel out the (x+2)'s. And then find the limit normally (with the restraint noted that x cannot equal -2).


In general, what you can do is check the limits from both sides. The limit coming from the left has to agree with the limit coming from the right. If they don't, then there is no limit.
 

Proud_Smash_N00b

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La Mirada, California
Ohh ic, thanks
when you check the limit from both sides do you plug in a value greater and less than the value than x is approaching as long as the absolute value of the 2 other values are equal?
 

AltF4

BRoomer
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Yea, like if you're checking the limit of:

f(x) = (x-1) (x+2) / (x+2)

as x approaches -2

You can do this by plugging in -1.9, then -1.99, then -1.999, and see what you get. Then make sure that value is the same as by plugging in -2.1, then -2.01, then -2.001, etc...
 

Darkurai

Smash Master
Joined
Aug 20, 2007
Messages
3,012
Code:
(a+4) (a+3)        (a+5) (a+3)
------------  *  -------------    
(a+2) (a+3)        (a+4) (a+1)
Okay, so...what do I do?
Do i cross cancel? Or do I cancel all three (a+3)'s?
Or do I cancel across?

Plz help
 

urdailywater

Smash Hero
Joined
Jul 12, 2008
Messages
5,563
Why does Algebra 2 suck so badly?

I want to go back to Geometry. Shapes were fun.


Okay: On a graph if there is only one line found on the x-axis going up and down - does that = to zero or is it an undefined line? Also, what's a good way to remember what it is?
 

brinboy789

Smash Champion
Joined
Aug 6, 2008
Messages
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Suffolk, Long Island, NY
Why does Algebra 2 suck so badly?

I want to go back to Geometry. Shapes were fun.


Okay: On a graph if there is only one line found on the x-axis going up and down - does that = to zero or is it an undefined line? Also, what's a good way to remember what it is?
up and down lines is undefined. right to left lines are zero. ( i think, lol ).
 

Meleeruler

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Logan, Utah
@Proud: First times the derivative of the second, plus the second times the derivative of the first.

First being the ln(x) and the second being the rest.

When multiplying anyway.
 

SkylerOcon

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Why does Algebra 2 suck so badly?

I want to go back to Geometry. Shapes were fun.


Okay: On a graph if there is only one line found on the x-axis going up and down - does that = to zero or is it an undefined line? Also, what's a good way to remember what it is?
It's undefined. A line with a zero slope would be a line found going straight left and right across the Y-axis.
 

Lixivium

Smash Champion
Joined
Mar 26, 2006
Messages
2,689
Code:
(a+4) (a+3)        (a+5) (a+3)
------------  *  -------------    
(a+2) (a+3)        (a+4) (a+1)
Okay, so...what do I do?
Do i cross cancel? Or do I cancel all three (a+3)'s?
Or do I cancel across?

Plz help
Assuming this is just simple multiplication,

You have (a+3) and (a+4) on both top and bottom. You can cancel those.

Remember that anything divided by itself is just 1. So (a+3)/(a+3) =1 and (a+4)/(a+4) = 1

So you get:

(a+5)(a+3)
-------------
(a+2)(a+1)

=

a^2 + 8a + 15
----------------
a^2 + 3a + 2
 

AltF4

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Lixivium is correct, except that you also have to add in the restrictions that

X =/= -3
and
X =/= -4


MojoMan:

It's impossible to have a triangle with 8, 3, and 3 sides. It's impossible to have a triangle where one side is greater than the other two combined.
 

Lixivium

Smash Champion
Joined
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Messages
2,689
Lixivium is correct, except that you also have to add in the restrictions that

X =/= -3
and
X =/= -4
Yeah I keep forgetting about that, you always think stuff like that isn't important, but then you end up with this:

a = b
a*b = b*b
ab = b^2
ab - a^2 = b^2 - a^2
a(b - a) = (b + a) (b - a)
a = b + a
a = a + a
a = 2a
1 = 2?
 

cman

Smash Ace
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May 17, 2008
Messages
593
Why does the integral from -4 to 2 of (2/(x^6))dx not exist?
 

Lavos

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299
Location
Purdue, West Lafayette
Anyone here too familiar with Differential Equations?

dx/dt = (3 -2)
.......... (2 -2) * x

That's supposed to be a matrix.

They made us take this class before Linear Algebra even though LA is supposed to come first, so I don't really know what an eigenvalue or an eigenvector is. This stuff is in my book, but it's a pretty terrible book to try and learn from. My professor is also a grad student who doesn't speak english very well.

Anyone know this stuff?
 

sephiroth90876

Smash Rookie
Joined
Dec 1, 2008
Messages
2
Location
Vidor, Texas
c

Why does the integral from -4 to 2 of (2/(x^6))dx not exist?
It does exist, the answer is infinity. If you look at the graph, its basically a really narrow parabola looking thing that stretches really far upward before coming back down. The -4 and 2 just so happen to be the zeroes of that function. Therefore, if you try to take the integral of that space, its just infinity.
 

smasher?o.0

Smash Journeyman
Joined
Oct 4, 2008
Messages
218
for math wizzes solve this problem
(i have tried but nothing comes to me)
k rules are you have to this (only one variable)
Variable
Equation
Work
Answer
Solution
FOLLOW THIS AND FORMAT IT LIKE SO
k the problem:
Popup cards sell for 4.50 a piece and come in boxes of 8. Regular cards are 3.00 and come in boxes of 12. If you sold twice as many boxes of regular cards as popup cards and made 82.50 how many cards of each type did you sell?

PLEASE HELP ME I HAVE TO DO A POSTER ON THIS WHOLE PROBLEM AND IT IS BLANK RIGHT NOW
 

tshahi10

Smash Ace
Joined
Oct 22, 2006
Messages
804
for math wizzes solve this problem
(i have tried but nothing comes to me)
k rules are you have to this (only one variable)
Variable
Equation
Work
Answer
Solution
FOLLOW THIS AND FORMAT IT LIKE SO
k the problem:
Popup cards sell for 4.50 a piece and come in boxes of 8. Regular cards are 3.00 and come in boxes of 12. If you sold twice as many boxes of regular cards as popup cards and made 82.50 how many cards of each type did you sell?

PLEASE HELP ME I HAVE TO DO A POSTER ON THIS WHOLE PROBLEM AND IT IS BLANK RIGHT NOW
4.5x8=36
3x12=36 a box
2x +x=82.50
x=27.5 dollars=27.5/36 a box=.76388 box of popup, and (.76388x2)=1.5277 of regular
regular =12 cards per boxx1.5277=18 and one third of regular cards
.76388x8=6.11 of popup cards.

it seems weird, but the thing is, that 82.50 is a bad number. if it was like 81, it would work out perfectly
 

smasher?o.0

Smash Journeyman
Joined
Oct 4, 2008
Messages
218
4.5x8=36
3x12=36 a box
2x +x=82.50
x=27.5 dollars=27.5/36 a box=.76388 box of popup, and (.76388x2)=1.5277 of regular
regular =12 cards per boxx1.5277=18 and one third of regular cards
.76388x8=6.11 of popup cards.

it seems weird, but the thing is, that 82.50 is a bad number. if it was like 81, it would work out perfectly
i didnt get anything you wrote
(my math teacher is an a**hat)
any other answers?
 

1048576

Smash Master
Joined
Oct 1, 2006
Messages
3,417
nvm don't think I can explain it any better

x is the total number of boxes.
 

Wardub

Smash Cadet
Joined
Mar 2, 2007
Messages
53
How do I evaluate y = (1+1/x)^x as x approaches infinity? Haven't done this stuff in a while.

Here's what I got

ln(y) = ln((1+1/x)^x)
= x* ln(1+1/x) >>> ln(1+1/x) / (1/x) which is 0/0. So I think I am suppose to use L'Hopitals rule.

But I keep messing up. I know the answer is e.

Also why can't I do (1 + 1/infinity)^infinity = (1+0)^infinity = 1. Obviously because I get 1 this way it isn't the correct answer, but what is wrong with that method?

Edit: Ok I get the right answer now, By getting -x^2/-(x^2+x) which simplifies to 1/(1+1/x) which is 1, so ln(y) = 1, and thus the answer is e. But I am still confused on why my reasoning for 1 is wrong, anyone know what went wrong?
 

digitalmaster287

Smash Journeyman
Joined
Aug 28, 2004
Messages
240
For the reasoning for 1, you cannot split up a limit that way. If it was 1 + 1/x + x, then you would take the limit of x--> infinity for each of the terms. It doesn't work when the entire thing is raised to an exponent simply because of the laws of limits not allowing you to do that. I can't really explain it any better than that.
 

Ange

Smash Lord
Joined
Dec 3, 2008
Messages
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Location
Sweden
How can

5(y + 2) = 18 -(1 - 3y)

be y=3,5?

Im not sure on how to actually come to the answer. :/
 

AltF4

BRoomer
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Ange:

5 * (y + 2) = 18 - (1 - 3y)
-distribute the 5-
5y + 10 = 18 - (1 - 3y)
-distribute the negative-
5y + 10 = 18 - 1 + 3y
-combine-
5y + 10 = 17 + 3y
-subtract 3y from both sides-
2y + 10 = 17
-subtract 10 from both sides-
2y = 7
-divide both sides by 2-
y = 7/2 or 3.5
 

Mr.Bazerkus

Smash Journeyman
Joined
Oct 16, 2008
Messages
383
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Interwebs
1. 3(Squareroot of 14) *(Square root of 21)
2. 2(Square root of 3) * 5(Square root of 3)
Multiply then simplify the radicals

()=square root sign
 

JLynn943

Smash Ace
Joined
May 4, 2008
Messages
511
Location
Allentown, PA
How do you find P and J in Jordan Canonical Form (For A=PJP^(1/2)) given a matrix A:

[1 -1 2]
[-2 0 4]
[-2 -2 6]

and det(A-lambda*I)= -1*(lambda-2)^2*(lambda-3) ?

edit: nevermind this, already took the final
 

Resting_Fox

Smash Master
Joined
Jul 16, 2001
Messages
3,565
Okay, I have a math question, mister super mod Math Whizz.

Last Year, I was on Christmas break from Westminster College in Fulton Missouri. I was typing up a log of memoirs, mostly recent, and the whole time a voice, a female voice, was over my shoulder and in my ear. Usually didn't say much worth repeating but it gave continual feedback like it had no life of its own, and after I had already ratted out most elements of the Great Cultural Hypocrisy and the finer details of the Grand Conspiracy, you know, things like Blabbing [lip-smacking syllable resemblances then denying it because it's the rules] and the Media's Mass Castration campaigns via direct assault on the human id, I got to the point where I recounted the time that ****ed up my entire idea of sound reality. Point Z, when I was sitting in biology, on Zoloft at the time, awake for 35 hours, and trying to keep up a conversation with my classmates, Zach and John, I got to the point where I asked them, "So are we really living in the Matrix." Zach said yes, My brain went into a furious tingling, and a feeling like all my consciousness had been sucked to the back. I looked to Zach and he pointed at me saying, "Yup, the Toxin." and John telling me, "Go Pee."And I fled toward the office, found the world blacking out halfway there and, thought I might have died, Since then reality had been pulling several nefarious tricks on me. Things and people behaving in ways beyond explanation, or rather, believability.
e.g. my dad referring to the blackout point the very same day before I'd even told him, the textbook named "anxiety attack" and then my Mom's invidious Dog Sheba not only talking often, but barfing up a marinara-covered meatball that it could have never ingested, and telling me, "Give up foul-mouth, you can't win."

When I had recounted that "Anxiety Attack", the female voice jumped at the opportunity, and told me, "Right, now time for you to die." I felt the exact same **** as the first time. Only I wasn't on anti-depressants [death pills] that could explain it away. The first time, it was easily discounted by the textbook explanation of a seratonine disorder in the brain. but the second time, I guess, the party messed up, or Westminster College serves Lab Rat Burgers, which needs to be investigated. You can't just have an anxiety attack at home on the computer. And less than a minute after the blackout had passed. I heard another voice, male, saying, "Don't you know Betas are different from Epsilons. Kind of...comforting isn't it." staging a weird, thrump of sensation that leapt up inside me exactly at the word comforting. And my old friend Ralph told me, casually, "You'll sweat." I then went up to my room and tried to sleep it off. Because I'd no reason to trust these people, even as representatives of the college, [which they didn't even present themselves as.]

Since then I'm not certain of anything but that we are in the Matrix, and I believe I may be trapped inside the College's own simulation. The students whom I assume were involved in the second "Anxiety Attack" seemed to be kind of, authoritative, as if they had ties to higher ups. Or just your 1984 Inner Party Memebers.

Anyway, since then Math has been Magic, and even my Nephew [who's hardly in sixth grade] is apparently better at it, [the magic aspect] than I am. the Math=Magic part doesn't bother me too much, but after my Roommate Derick Dailey poisoned me with a cookie, conspired with the police to have lies reported officially and to have him pretentiously left above suspicion and above the law. And then, while i was in the hospital recovering, and he harassed me on the phone whenever I spoke to someone else who called, hearing his voice intercede each time [an impossible but made real happening] And all the other begrudging students, or unjustified maligned took their turn at my belongings, musical, or otherwise. I've had this huge problem.

See every time I play guitar now, there's a massive crank-up of my natural hallucinations. Only they don't just pertain to the people physically around me. I'll be hearing the voices of Mrs. Carey, my old Latin teacher, and most obnoxiously people from the College, to such an extent that it fundamentally ruins the art form. Much like influential crap-downning ruins Most of the mass media. I could think of only one explanation for this entirely impossible phenomenon. It had to be Math Magic, or Mathic.

Now here's where the actually pragmatic question comes in. I assume somehow, these malefactors have mathed a communication channel onto my guitar and even more strong communication channels on certain compositions. Strangely though, these are not limited to the number I had with me at the time of my attendance and subsequent hospital visit, between which times my guitar and gear was open to such manipulations. This never absent flux of their communication over my sounds, basically ruined my whole purpose in creating my own music [to safely fill the inculcated aesthetic need with a home-made clean product] and really had an impact on my feeling about the value of life itself. I've already committed suicide with pills, and I just can't seem to cease existing.

I have in my posession, one College Algebra Book, and an Elemantary statistics book. So I need to know which chapter can I consult to shut off whatever communication channels they established on my guitar, amp, or whatever device. Prayers to the Gods did nothing, so I have to take the magic into my own command. There's one chapter on which a picture is placed at the front, depicting a dam from a top-down view. It looks sort-of like an insect head drowning, or communicates the idea of a reduction of flux. But none of those formulae have worked for me.

I've already graphed death on the main malefactor [code name Hentai] and later the president [purely in thought though] by some hardly natural impulse, which I suspect must've been in the subliminal messages of Coldplay's X&Y with the shading of the are between a Parabola x^2 - 3 and and the line x=0 representing the frontal lobe.

Then I performed a similar function on myself. This one on a TI-82 calculator. shading an X^3 function's overlap with an X^2-2 and had something that felt like a stroke or a black electric mass rush up from my neck through the left side of my brain. This was how I confirmed that math had definitely become Magic since the second download into an alternate Reality.

So if the functions in my Algebra Book are not working and Dylan Bannon, the actual Maynard [or singer of tool, my High School Band] mathed a Musical Death on me when I played Viginti Tres Backwards as I did because Mrs. Carey lied and told me, "If you really want to off yourself, listen to it backwards" I figured it would just math a stroke or some reasonable death. The Pun, "Forget you Travis." Was obvious. As well as "We get to Trace."Referring to the part where the flames synchronize with Jambi/Bambi. As if Lipan Conjuring wasn't enough...

[Oh yeah Dylan Gloat over it. Betas never get tired of gloating even though they fight continually from an unfair advantage. [Eight Extra hours, awake while asleep] You never stop winning. Especially when you chose to victimize people who have no real chance of countering. Why don't you go repeatedly stab some new-born children or something. In principle it's the same. ]

...Is it possible I'm going to have to pore for months over several different math books, like all the way up to Calculus, just to achieve homeostasis. Or would it be better explained as "Beta decrees it, Heil Hitler, and F*** You!" and no matter what Math I study the reality malfunction will continue because Dylan is an inner party member with a grudge and more power than can satisfy his boredom.

Put more simply. Exponential functions apply to Angelology right. and Logarithmic Functions apply to Music. But since Angelology is involved with Music, I suppose both would be handy for a musician [mostly in tone quality and variation]. But what funtions apply to long distance, across the world communications and more particularly negating them. Is it Inverse Functions or Regular Functions?

Oh yeah, and little Travises, how you know what applies to a math formula is by seeking carefully for syllables or effects around you when you're writing it and/or solving it. Often it's by talking scratches, or Fricative Thought Projection. And is if that weren't exclusive enough, you also have to be in favor of Athena for any of it to even happen.
 

#HBC | Mac

Nobody loves me
BRoomer
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Dec 5, 2005
Messages
5,086
Location
Mass
derivatives and explanation for: arctanx, arcsinx, arccosx, logbase10 of x, logbase x of 10, 100^x, 10^2x

integrals and explanations for: lnx, cos^2(x)sinx, cos^3(x)sin(x), cos^3(x)sin^2(x), cos^4(x)sin^2(x), sin^3(x)cos^2(x), sin^3(x)cos^2(x)

I dunno if all of these an even be done, but I had something like these on previous tests and i didnt do well on them and I have a test tomorrow.

Help please =/
 

DTKPch

Smash Journeyman
Joined
Feb 4, 2008
Messages
369
How do you find P and J in Jordan Canonical Form (For A=PJP^(1/2)) given a matrix A:

[1 -1 2]
[-2 0 4]
[-2 -2 6]

and det(A-lambda*I)= -1*(lambda-2)^2*(lambda-3) ?

edit: nevermind this, already took the final
Just wondering, what Linear Algebra class are you in? Because we covered Jordan Canonical forms, but never really had to worry about P^(1/2) stuff, or at least I don't remember doing stuff like that.
 

Proud_Smash_N00b

Smash Ace
Joined
Jul 4, 2007
Messages
873
Location
La Mirada, California
I need help with Optimization problems. I know it's just finding the derivative and finding the max or min according to the problem but how do you know what is the equation to differentiate and stuff like that? I'm goin over it right nao in class and the assignments are really hard.

For example. Find a point on the curve x^2+y^2=1 that is closest to (2,0). I know that that point is (1,0) (common sense ftw) but idk how to find it mathematically by using an equation and its derivative
 

marthanoob

Smash Journeyman
Joined
Oct 23, 2007
Messages
272
Location
The House of Polemarchus
I need help with Optimization problems. I know it's just finding the derivative and finding the max or min according to the problem but how do you know what is the equation to differentiate and stuff like that? I'm goin over it right nao in class and the assignments are really hard.

For example. Find a point on the curve x^2+y^2=1 that is closest to (2,0). I know that that point is (1,0) (common sense ftw) but idk how to find it mathematically by using an equation and its derivative
Distance equation should work.
First solve the equation for y. So, sqrt(1-x^2).
Then plug all that into the distance formula.
D = sqrt( [0-sqrt(1-x^2)]^2 + [0-x]^2 )
Then take the derivative of that and solve for when D' equals 0 which I am too lazy to do. Hope this helps.
 

AltF4

BRoomer
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Dec 13, 2005
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Yes, marthanoob is correct. You have to ask yourself the question "What am I trying to maximize/minimize?"

In this case, you are minimizing the distance. So use the distance formula.
 

Death

Smash Lord
Joined
Dec 7, 2003
Messages
1,276
I'm having a bit of trouble on Maximum-Minimum Values of Quadratic Functions (because I missed all of least week swimmig :mad:).

Anyway, the question is:

A rectangular field is to be enclosed with 600 m of fencing. What is the maximum area that can be enclosed and what dimensions will give this area?

So, the maximum area without turning the field into a square is < 22 500 square meters. However, my stupid book says 150 m x 150 m, which would make a square and this question would be pointless.

So the greatest whole number dimensions are: 149 x 151? Does anyone know how to set this up using a quadratic function? :confused:

Also, a rectangular field is to be enclosed and divided into two sections by a fence parallel to one of the sides using a total of 600 m of fencing. What is the maximum area that can be enclosed and what dimensions??
 

marthanoob

Smash Journeyman
Joined
Oct 23, 2007
Messages
272
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The House of Polemarchus
I'm having a bit of trouble on Maximum-Minimum Values of Quadratic Functions (because I missed all of least week swimmig :mad:).

Anyway, the question is:

A rectangular field is to be enclosed with 600 m of fencing. What is the maximum area that can be enclosed and what dimensions will give this area?

So, the maximum area without turning the field into a square is < 22 500 square meters. However, my stupid book says 150 m x 150 m, which would make a square and this question would be pointless.

So the greatest whole number dimensions are: 149 x 151? Does anyone know how to set this up using a quadratic function? :confused:

Also, a rectangular field is to be enclosed and divided into two sections by a fence parallel to one of the sides using a total of 600 m of fencing. What is the maximum area that can be enclosed and what dimensions??
A square is a type of rectangle.
 
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