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General => The Lobby => Topic started by: on December 31, 1969, 04:00:00 PM

Poll
Question: MATH BOARD
Option 1: yes votes: 1
Option 2: no votes: 4
Option 3: +c votes: 2
Option 4: +science votes: 4
Option 5: plz votes: 2
Title: Obligatory Math Help Thread
Post by: [REDACTED] on February 26, 2008, 08:13:17 PM
Please help. ;-;
Title: Re: hey guys product/quotient rule y/n
Post by: Daddy on February 26, 2008, 08:14:53 PM
I think a mathematics and science board would be cool.
Title: Re: hey guys product/quotient rule y/n
Post by: strongbad on February 26, 2008, 08:19:15 PM
A general school board pls
Title: Re: hey guys product/quotient rule y/n
Post by: sans culottes on February 26, 2008, 10:45:58 PM
i voat for the monkees they make good songs.
Title: Re: hey guys product/quotient rule y/n
Post by: ncba93ivyase on February 27, 2008, 03:30:17 AM
Quote from: JMV290 on February 26, 2008, 08:14:53 PM
I think a science board would be cool.
srsly
Title: Re: hey guys product/quotient rule y/n
Post by: guff on February 27, 2008, 12:34:47 PM
shut up felt
Title: Re: hey guys product/quotient rule y/n
Post by: [REDACTED] on February 27, 2008, 01:30:35 PM
Quote from: Commodore Guff on February 27, 2008, 12:34:47 PM
shut up felt
.
Title: Re: hey guys product/quotient rule y/n
Post by: YPrrrr on February 27, 2008, 01:31:29 PM
Just had a test on this today...
Title: Re: hey guys product/quotient rule y/n
Post by: [REDACTED] on February 27, 2008, 01:32:33 PM
Quote from: Your Posting Rival on February 27, 2008, 01:31:29 PM
Just had a test on this today...
Really?
Title: Re: hey guys product/quotient rule y/n
Post by: YPrrrr on February 27, 2008, 01:33:24 PM
Quote from: su??? n????o? on February 27, 2008, 01:32:33 PM
Really?
If this is what I think it is, then yes... or at least the product rule.
Title: Re: hey guys product/quotient rule y/n
Post by: [REDACTED] on February 27, 2008, 01:35:47 PM
Quote from: Your Posting Rival on February 27, 2008, 01:33:24 PM
If this is what I think it is, then yes... or at least the product rule.
Is it something like this:
f(x)g(x)=h(x)
h'(x)=f(x)g'(x)+g(x)f'(x)
Title: Re: hey guys product/quotient rule y/n
Post by: YPrrrr on February 27, 2008, 01:36:36 PM
Quote from: su??? n????o? on February 27, 2008, 01:35:47 PM
Is it something like this:
f(x)g(x)=h(x)
h'(x)=f(x)g'(x)+g(x)f'(x)
Yep, that's it
Title: Re: hey guys product/quotient rule y/n
Post by: superclucky on February 27, 2008, 07:01:52 PM
Quote from: Commodore Guff on February 27, 2008, 12:34:47 PM
shut up felt
felt requests that you be friends with him regardless of his face
Title: Re: hey guys product/quotient rule y/n
Post by: V on February 27, 2008, 07:16:32 PM
get out, Felt
Title: Re: How do I use the Chain Rule? ;________;
Post by: [REDACTED] on February 29, 2008, 01:30:43 PM
Please help. ;-;
Title: Re: How do I use the Chain Rule? ;________;
Post by: YPrrrr on February 29, 2008, 01:34:45 PM
What part do you need help with?
Title: Re: How do I use the Chain Rule? ;________;
Post by: [REDACTED] on February 29, 2008, 01:37:19 PM
Quote from: Your Posting Rival on February 29, 2008, 01:34:45 PM
What part do you need help with?
What is the exact rule?
I know you take a function and make it into two composite functions, but I don't know how you differentiate from there.
Title: Re: How do I use the Chain Rule? ;________;
Post by: Daddy on February 29, 2008, 01:38:54 PM
Say that you had


(5x2+2x)2 and you wanted derivative this is what you'd do

Substitute 5x2+2x with U so you'd have U2 and then multiply it by (5x2+2x)'

so U2' * (5x2+2x)' =

2U(10x +2)  =

2(5x2+2x) (10x+2) =

(10x2 + 4x) (10x + 2) =

100x3+20x2 + 40x2+8x =

100x3+60x2+8x

I suck at explaining stuff, but that's right.
Title: Re: How do I use the Chain Rule? ;________;
Post by: YPrrrr on February 29, 2008, 01:50:24 PM
Quote from: suÃ,,±ÊÊ‡ nɐǝʇɔoÉ” on February 29, 2008, 01:37:19 PM
What is the exact rule?
I know you take a function and make it into two composite functions, but I don't know how you differentiate from there.
It's all about derivitives...

Using JMV's example: (5x2+2x)2

so you find the derivitive of f(x), which is 2, and multiply it by g(x) which equals (5x2+2x) * g'(x), which is (10x+2)

So in the end, it would be 2(5x2+2x)(10x+2)

In summary... chain rule = f '(g(x))g'(x)

f '(x) = 2
g(x) = (5x2+2x)
g'(x) = (10x+2)

that is, if what i'm thinking of is correct...
Title: Re: How do I use the Chain Rule? ;________;
Post by: Daddy on February 29, 2008, 01:52:00 PM
Oh shit.  Why did I add them?

fixed so it multiplies.
Title: Re: How do I use the Chain Rule? ;________;
Post by: [REDACTED] on February 29, 2008, 02:13:15 PM
Ok, I now understand it.
I just need to make a composite function of the function I want to differentiate, h(x)=f(g(x)).
Then find f' and g'. Then, multiply f'(g(x) by g'(x).
Title: Re: How do I use the Chain Rule? ;________;
Post by: Daddy on February 29, 2008, 02:16:37 PM
Quote from: suÃ,,±ÊÊ‡ nɐǝʇɔoÉ” on February 29, 2008, 02:13:15 PM
Ok, I now understand it.
I just need to make a composite function of the function I want to differentiate, h(x)=f(g(x)).
Then find f' and g'. Then, multiply f'(g(x) by g'(x).
dats wut i said except i used u
Title: Re: How do I use the Chain Rule? ;________;
Post by: YPrrrr on February 29, 2008, 02:49:05 PM
Quote from: JMV290 on February 29, 2008, 02:16:37 PM
dats wut i said except i used u
And used addition originally caterpie;
Title: Obligatory Math Help Thread
Post by: 6M69I69B9 on February 29, 2008, 05:28:49 PM
my head is broken, please help the freshman with algebra.



Right triangle

A : 6^2
B : 6^2
C : Square root of 3.

Find C.


I do 6^2 to both A and B, which are 36. Next, I add them together to get 72.

Then I do 3x72, which equals 216.

Then I have to find the square root of that.



Did I do it right? I know I have to get the square root, but I don't have a calculator right now.
Title: Re: Obligatory Math Help Thread
Post by: [REDACTED] on March 02, 2008, 10:32:45 PM
You did not get C right. Try again.
Title: Re: Obligatory Math Help Thread
Post by: UnagiPower on March 03, 2008, 03:16:12 PM
At least you don't have to do proofs.  :(

Which are hard if you don't pay attention in class/read the textbook.
Title: Re: Obligatory Math Help Thread
Post by: Gladjaframpf on March 04, 2008, 03:02:44 PM
I'm confused. Are A, B, and C the side lengths of the triangle? If so, you can't possibly have a right angle triangle with those side lengths, so something is wrong. Also, you're trying to find C, but you already said it was the square root  of 3. I'm just not sure what you're trying to do here.
Title: Re: Obligatory Math Help Thread
Post by: Squirtlejazz on March 04, 2008, 05:01:24 PM
A2+B2=C2
But that isn't possible on your triangle.
Title: halp, half angles
Post by: C.Mongler on March 04, 2008, 09:25:02 PM
sin u = 5/13

find sin (u/2) plz
Title: Re: halp, half angles
Post by: [REDACTED] on March 05, 2008, 02:16:55 PM
Use the half angle formula, silly.
Also, does it give you what quadrant or region the angle is located in?
Use the pythagorean trig identities to find cos u.
Here's the half angle formula:
(http://home.alltel.net/okrebs/Ch10-15.gif)
Title: Re: Obligatory Math Help Thread
Post by: [REDACTED] on March 07, 2008, 04:15:15 PM
Ok guys, I need help again.
(http://www.codecogs.com/eq.latex?%20\sqrt{xy}=x-2y)
I need to find dy/dx of this.
I got: (http://www.codecogs.com/eq.latex?%20\frac{dy}{dx}=\frac{2\sqrt{x}-\sqrt{y}(\sqrt{y})}{\sqrt{x}(\sqrt{x}+4\sqrt{y})})
Title: Re: Obligatory Math Help Thread
Post by: Tomboh on March 07, 2008, 04:18:29 PM
hay mib why arent you in geo h?
Title: Re: Obligatory Math Help Thread
Post by: 6M69I69B9 on March 07, 2008, 05:46:32 PM
Quote from: Tomboh on March 07, 2008, 04:18:29 PM
hay mib why arent you in geo h?
my head is broken, please help the freshman with algebra.



Right triangle

A : 6^2
B : 6^2
C : Square root of 3.

Find C.


I do 6^2 to both A and B, which are 36. Next, I add them together to get 72.

Then I do 3x72, which equals 216.

Then I have to find the square root of that.



Did I do it right? I know I have to get the square root, but I don't have a calculator right now.
Title: Re: Obligatory Math Help Thread
Post by: [REDACTED] on March 07, 2008, 06:49:46 PM
Quote from: Original_MIB on March 07, 2008, 05:46:32 PM
my head is broken, please help the freshman with algebra.



Right triangle

A : 6^2
B : 6^2
C : Square root of 3.

Find C.


I do 6^2 to both A and B, which are 36. Next, I add them together to get 72.

Then I do 3x72, which equals 216.

Then I have to find the square root of that.



Did I do it right? I know I have to get the square root, but I don't have a calculator right now.

DON'T USE A CALCULATOR.
Have they taught you how to factor radicals?
Could you scan the problem? You may have wrote the wrong notation, thus you are having problems.
a=6.
b=6.
This is why it is causing you problems.
a2+b2=c2 by the way of the Pythagorean theorem.
So we get 72=c2