Jika f(x+1) = 3 x^{2} + 5x + 7 dan f'(x-1) = - x^{2} , nilai x yang memenuhi adalah ....

f(x+1)= 3x²  + 5x + 7
f(x) = 3(x-1)² + 5(x -1) + 7
f(x)= 2x² - 6x + 3 + 5x - 5 + 7
f(x)= 2x² - x + 5
f' (x)=  4x - 1
f'(x-1) = 4(x-1) - 1
f'(x-1) = 4x - 4 - 1
f'(x-1) = 4x - 5 ...(1)
.
f '(x) = - x² .....(2)
.
(1) = (2)
4x - 5 = - x²
x² + 4x - 5 = 0
(x + 5)(x -1) =0
x = - 5  atau x = 1