confused, please help

[Guest]

Ok, consider the function y = f(x) = 2x^2-2x,

I have to find:

a) what f(x+h) equals,
b) what f'(x) at x = 0,
c) what the equation of the tangent line to the curve at the point (3, 12) is?

can you point me in the right direction on a and c,

for b I have f' = 12x^2, so 12(0)^2 = 0?

Thanks in advance!

 

[ChaoticLlama]

keep in mind for a general polynomial:

if f(x) = x^n

then f'(x) = n * x^(n - 1)

 

[Guest]

im sorry i dont understand

 

[stapel]

He was reminding you of the derivative rule for polynomial terms, so you can try to correct your answer to (b).

Eliz.

 

[Guest]

Eliz.
Thanks, I see what I was doing now...
So now I have f' = 4x-2, and at x=0, =-2? Does that sound right? Any help on the other two?
Thanks

 

[Lizzie]

Chris,
That's what I got. I got f'(x)=4x-2 and f'(0)=-2.
-Lizzie

 

[Lizzie]

Also, I think that a) is 2(x+h)² - 2(x+h).