Tuesday, June 21, 2011

What is derivative of f(x)=(2x+1)^2+(2x-2)^2+2(4x^2-2x-2)

We notice that the 3rd term is the result of the product
(2x+1)(2x-2) = (4x^2 - 2x - 2).


If we'll note (2x+1) by a
and (2x-2) by b, and we'll re-write the equation, we'll get a perfect
square:


y=a^2 + 2ab + b^2


y =
(a+b)^2


f(x) = y =
(2x+1+2x-2)^2


We'll combine like
terms:


y = (4x-1)^2


Now, we'll
differentiate both sides, with respect to x:


dy/dx =
2*(4x-1)*(4x-1)'


dy/dx =
2*(4x-1)*4


dy/dx =
8*(4x-1)


We'll remove the
brackets:


dy/dx = 32x -
8


The first derivative of the given function
is f'(x) = 32x - 8.

No comments:

Post a Comment

What accomplishments did Bill Clinton have as president?

Of course, Bill Clinton's presidency will be most clearly remembered for the fact that he was only the second president ever...