Posted by **John** on Wednesday, May 14, 2008 at 5:42pm.

Find the Derivative of F(x)=4x2(the previous 2 is squared)-2x

- Pre Calculus -
**Damon**, Wednesday, May 14, 2008 at 5:57pm
y = 4 x^2 -2 x

in general derivative of x^n = n x^(n-1) so

dy/dx = 4 * 2 x^1 - 2 x^0

which is

8 x - 2

- Pre Calculus -
**Damon**, Wednesday, May 14, 2008 at 6:03pm
Now if you have not had that relation you have to do it from the definition

dy/dx = (y at x+h - y at x) /h as h-->0

here

y at x+h = 4 (x+h)^2 - 2 (x+h)

= 4 x^2 + 8 x h +4 h^2 - 2 x - 2 h

y at x = 4 x^2 - 2 x

difference over h = 8 x + 4 h - 2

as h-->0 that is

8 x - 2

as we already knew

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