Question

(FCC-SP) - O valor de ab²-a³ para a= -x/2 e b=2x é:

A) 17/8x³
B) -17/8x³
C) -15/8x³
D) -11/6x³
E) -13/6x³

Answer 1

ab² - a³

$\frac{-x}{2} * (2 x^{2} ) - (\frac{-x}{2} ) ^{3}$
$\frac{-x}{2} * 4x^{2} - ( \frac{-x ^{3} }{8} )$
$\frac{-4 x}{2} ^{3} + \frac{x}{8} ^{3}$
Desenvolvendo o MC vem:
$\frac{-16x+ x^{3} }{8}$
= $\frac{-15x}{8} ^{3}$

Resposta letra C