Need Math Help?

[Sinz]

Problems. :/
Let f(x) = 3 + 2x + 4e^x
find f^-1(7).

I am stumped as how start this one.

 

[UTDZac]

Problems. :/
Let f(x) = 3 + 2x + 4e^x
find f^-1(7).

I am stumped as how start this one.

This will help you get started: http://www.uncwil.edu/courses/mat111hb/functions/inverse/inverse.html

I read the first few paragraphs, it was very informative.

 

[Solaris1110]

Could someone give me the lowdown of the sine and cosine lawss?
The way my teacher explained it was the most confusing **** I've ever seen lol.

 

[[oni]LoKo]

Could someone give me the lowdown of the sine and cosine lawss?
The way my teacher explained it was the most confusing **** I've ever seen lol.

What do u mean laws? Like how to use them? The way I remembered them is "soh cah toa"
SOH => Sin = Opposite/Hypotenuse
CAH => Cosine = Adjacent/Hypotenuse
TOA => Tangent = Opposite/Adjacent

Like what is it that you're confused about? 'Cause these laws get deeper than just their definition ( and are -super- useful once you master them and the unit circle)

 

[Solaris1110]

I mean like solving triangles that dont have right angles. ex: the only known variables are one angle and a side adjacent to it.

 

[POKE40]

I mean like solving triangles that dont have right angles. ex: the only known variables are one angle and a side adjacent to it.

Law of Sine:

Law of Cosine:

and you are doing Law of Tangents?
I'll post explanations soon.

 

[Solaris1110]

i'm guessing I'll be dealing with the Tangent one soon, so a look into it would help a lot.

lol, usually i'm too tired to understand anything during class so I just write it down and figure it out at home... especially since its 2x more accelerated than math pure.

 

[POKE40]

i'm guessing I'll be dealing with the Tangent one soon, so a look into it would help a lot.

lol, usually i'm too tired to understand anything during class so I just write it down and figure it out at home... especially since its 2x more accelerated than math pure.

If the Law of Tangent is in the book, the chances are way higher for you to need to know that. But if it is not in the book, don't stress.
(I haven't even gone over it lol.)

I don't think you'll have to learn this in Geometry (that is what you're taking right?)
If you're taking trig, it might be in there. (My trig book last year for some reason didn't go over Law of Tangent)

Law of Tangent:

 

[Sraigux]

What steps would I go about to solve this problem?

(x/3) + (y/4) + (z/2) = 7

(x/6) + (y/2) + (z/6) = 6

(x/3) + (y/2) + (z/2) = 9

I need to find z x and y

 

[POKE40]

What steps would I go about to solve this problem?

(x/3) + (y/4) + (z/2) = 7

(x/6) + (y/2) + (z/6) = 6

(x/3) + (y/2) + (z/2) = 9

I need to find z x and y

Systems of Equations or Matrices is the best way.

I prefer Matrices.

 

[Corpsecreate]

What steps would I go about to solve this problem?

(x/3) + (y/4) + (z/2) = 7

(x/6) + (y/2) + (z/6) = 6

(x/3) + (y/2) + (z/2) = 9

I need to find z x and y

EQ3 - EQ1 gives you y/4 = 2 so y = 8,
EQ3 - 2EQ2 gives you -4 + z/6 = -3 ---> z = 6
(x/3) + (8/4) + (6/2) = 7. ---> x = 3(7-2-3) = 6

x = 6
y = 8
z = 6

 

[Arturito_Burrito]

Ok my Hw is due at at midnight so i could really use the help. I only have 1 problem left but i'm stuck half way through =\ the question is:

Find equations of the two tangent lines to the graph of f(x) = 3x^2 that pass through the point (1, -45).

F'(x) = 6x

and one equation is y= 6x -51 I believe, the problem asks for a line with a positive slope and a negative slope though and i have no idea how to find the 2nd one.

edit: y = 6x -51 is wrong so 2 more tries for me

 

[POKE40]

Ok my Hw is due at at midnight so i could really use the help. I only have 1 problem left but i'm stuck half way through =\ the question is:

Find equations of the two tangent lines to the graph of f(x) = 3x^2 that pass through the point (1, -45).

F'(x) = 6x

and one equation is y= 6x -51 I believe, the problem asks for a line with a positive slope and a negative slope though and i have no idea how to find the 2nd one.

edit: y = 6x -51 is wrong so 2 more tries for me

y = 6x - 51 is wrong?!?!

What the flip?
IS there any other information that is given?

 

[Arturito_Burrito]

I'm uploading a picture right now its pretty big so i'll just link it in min.

edit nvm the problem got smaller when i uploaded it and now you can't see it....

The entire thing is:

Find equations of the two tangent lines to the graph of f(x) = 3x^2 that pass through the point (1, -45).
y(x) =____________ (line with negative slope)
y(x) =____________ (line with positive slope)






I figured out f'(x)=6x idk if thats where i messed up but it seems like the only place it could have happened.

 

[moogle]

Ok my Hw is due at at midnight so i could really use the help. I only have 1 problem left but i'm stuck half way through =\ the question is:

Find equations of the two tangent lines to the graph of f(x) = 3x^2 that pass through the point (1, -45).

F'(x) = 6x

and one equation is y= 6x -51 I believe, the problem asks for a line with a positive slope and a negative slope though and i have no idea how to find the 2nd one.

edit: y = 6x -51 is wrong so 2 more tries for me

This is what I typed in Notepad in the time it took me to figure this out:
(If you want me to explain any of this, I can.)

y=mx+b

x=0
tangent line: y=0

x=1
tangent line: y=6x-3

x=2
tangent line: y=12x-12

x=k
tangent line: y=6kx-3k^2 (I'm just kinda finding the pattern)

plug in point (1,-45) and solve for k

-45 = 6k-3k^2
3k^2-6k-45 = 0
3(k-5)(k+3) = 0
k=5, k=-3

so you have
y=30x-75
and
y=-18x-27

 

[Sinz]

Edit: Nevermind, he got it.

 

[POKE40]

Good stuff Moogle
0.o

 

[AltF4]

Do try to keep this from being a "Do my homework for me" thread. That's just plain cheating on your homework. And do recall that this is a public forum. It's real easy for teachers to google for their own homwwork / test questions and see who's asking for answers.

 

[Arturito_Burrito]

do you mind explaining from x=k? I do have another problem like this and i would like to try and figure it out by my self.


edit: I feel like i could understand it better over aim if you don't mind.

 

[Teczer0]

Can someone explain to me Phasors.

I wasn't sure if this is a math or physics related question so I just asked it here.

From what I know, phasors are used to transform things in the form:

I(t) = I cos(wt + p) [w = omega, angular frequency; p = phi, phase shift]

to the form I(t) = I e^i(wt+p)

But I have a question in my electromagnetic fields class that doesn't include a time variable.

How do I deal with that?

 

[Corpsecreate]

 

[Sraigux]

Thanks for the help

 

[brawlpro]

Can someone please tell me the recursive formula for "3,6,12,24..." and explain how you got it so I can know from now on? You might need a smart *** calculator for it or something.

 

[Teczer0]

Can someone please tell me the recursive formula for "3,6,12,24..." and explain how you got it so I can know from now on? You might need a smart *** calculator for it or something.

Don't the numbers just double?

Are you asking for a mathematical relationship?

Maybe X(n+1) = Xn*2?

 

[momaspeare]

Hy guys
I didn't understand how 1=0...
Can anyone help me to understand it please because our math teacher said that 1 can't be 0.
So if you could help me to discuss with him I were very thankful

 

[Teczer0]

Hy guys
I didn't understand how 1=0...
Can anyone help me to understand it please because our math teacher said that 1 can't be 0.
So if you could help me to discuss with him I were very thankful

Let x = 1 – 1 + 1 – 1 + 1 …
X = (1 – 1) + (1 – 1) + (1 – 1) +…
X = 0 + 0 + 0 + …
X = 0
Let x = 1 – 1 + 1 – 1 + 1 …
X = 1 + (-1 + 1) + (-1 + 1) + (-1 + 1) …
X = 1 + 0 + 0 + 0 + 0…
X = 1
Thus,
1 = 0

Satisfied? I have an entire thread for this stuff. It's on the next page of threads.

Something like that

 

[Hydra.]

2x=-3y+10

Rewrite the equation so that y is a function of x.

I subracted 10 from each side so now I have 2x-10=-3y and I got stuck.

 

[Teczer0]

Divide by -3 on both sides.

 

[Hydra.]

Divide by -3 on both sides.

Haha thank you, that was so obvious, I just couldn't remember how we did it in class Friday. xD

 

[Teczer0]

Haha thank you, that was so obvious, I just couldn't remember how we did it in class Friday. xD

LOL it happens.

I was doing my Linear algebra hw and I forgot how to do

0-1 for like a good 20 seconds

 

[brawlpro]

Don't the numbers just double?

Are you asking for a mathematical relationship?

Maybe X(n+1) = Xn*2?

yes but i don't know how to write it. like a question also told me to find the 1st four terms of the sequence defined "U1 = 17, Un-1+8 where n>2

I just dont know how to write a recursive formula, i think it's something like the question.

 

[nux23]

can someone please explain algorithms to me? trying to solve a cube here >.<

 

[POKE40]

can someone please explain algorithms to me? trying to solve a cube here >.<

You mean this blasted thing:

:embarrass

I'll never learn how to get it solved.

 

[nux23]

no, I mean this thing:

I could solve the 3x3x3 w/o algorithms

 

[Death]

Agh, school is back and so is math! I got a few questions that I either don't seem to remember or never learned in the first place

a) Log x + log y = 0.5 . What is xy?

b) Log x = 3, find x. Log y = 1.4, find y.

c) Find ln 10.

d) Find log to base 2 of 1024 ( this is just 10 is it not?

I've tried looking for answers on the internet but websites only supply either complex questions or just the formulas. For example, if log x = 3, then isn't x just 10^3 = 1000??

PLEASE HELP!!

 

[Corpsecreate]

Agh, school is back and so is math! I got a few questions that I either don't seem to remember or never learned in the first place

a) Log x + log y = 0.5 . What is xy?

b) Log x = 3, find x. Log y = 1.4, find y.

c) Find ln 10.

d) Find log to base 2 of 1024 ( this is just 10 is it not?

PLEASE HELP!!

a) Log x + Log y = 0.5 --> log xy = 0.5 (using the rule that log(A) + log(B) = log(AB)) ---> xy = 10^0.5 so xy = sqrt10

b) Log x = 3 ---> 10^3 = x, x = 1000.
Log y = 1.4 = 7/5. 10^(7/5) = y, y = 25.1188 or the 5th root of 10,000,000

c) Dont know exactly what it means by find ln 10. ln 10 is just ln 10 / lne, lne is 1 so ln 10 = ln10.... but that doesnt really answer anything does it?

d) yeah its just 10

 

[momaspeare]

hey guys
i have a question:
our teacher told us that phylosophi and maths are the base subjects and everything is build on these...
is this sentence correct? me and my friend thought that chemistry is also one of the base subjects...
maybe you can help me

 

[moogle]

hey guys
i have a question:
our teacher told us that phylosophi and maths are the base subjects and everything is build on these...
is this sentence correct? me and my friend thought that chemistry is also one of the base subjects...
maybe you can help me

In all seriousness, your teacher might have an argument for why philosophy and math are the two bases for all other areas or study, but I'd say the statement "math is a basis for many other subjects" is more accurate and less.... assuming.

 

[Dodongo]

Alt,
Could Math microwave a burrito so hot that he himself could not eat it?

 

[momaspeare]

Oh yes the picture helped me to understand...a little bit...
Thanks for your help