Question

simplificando a expressão$\frac{ x^{2} -9}{3x+15}. \frac{ x^{2}+10x+25}{2x-6}. \frac{1}{ x^{2} +8x+15}$ obtemos:


a- 1/3
b- 1
c- 1/2
d- 1/6

Answer 1

R: Letra D

veja

$\frac{ x^{2} -9}{3x+15} \times \frac{ x^{2} +10x+25}{2x-6} \times \frac{1}{ x^{2} +8x+15} =$

$\frac{(x+3)(x-3)}{3(x+5)} \times \frac{(x+5)^2}{2(x-3)} \times \frac{1}{(x+3)(x+5)} =$

cancela  x+3 com x+3
x-3 com x-3
x+5 com x+5

fica

$\frac{1}{3} \times \frac{1}{2} \times1= \frac{1}{6}$