Question

f(x) = -x^3 + 3x + 9

f'(x) trebuie sa dea 3(1-x)(1+x)

Mie mi-a dat -3x +3 + 0 => 3(1-x)(1+x)

Answer 1

 

$\displaystyle\bf\\f(x) = -x^3 + 3x + 9\\\\f'(x)=-3x^2+3+0\\\\f'(x)=-3x^2+3\\\\f'(x)=3(-x^2+1)\\\\f'(x)=3(1-x^2)\\\\Folosim formula: a^2-b^2=(a-b)(a+b)\\\\\boxed{\bf~f'(x)=3(1-x)(1+x)}$