Obligatory Math Help Thread

[YPrrrr]

What part do you need help with?

[[REDACTED]]

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.

[Daddy]

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.

[YPrrrr]

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...

[Daddy]

Oh shit.  Why did I add them?

fixed so it multiplies.

[[REDACTED]]

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).

[Daddy]

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

[YPrrrr]

dats wut i said except i used u

And used addition originally caterpie;

[6M69I69B9]

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.

[[REDACTED]]

You did not get C right. Try again.

[UnagiPower]

At least you don't have to do proofs. 

Which are hard if you don't pay attention in class/read the textbook.

[Gladjaframpf]

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.

[Squirtlejazz]

A²+B²=C²
But that isn't possible on your triangle.

[C.Mongler]

sin u = 5/13

find sin (u/2) plz

[[REDACTED]]

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: