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.
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