Question

Помогите пожалуйста.

Answer 1

$x^a*x^b=x^{a+b} \\ \frac{x^a}{x^b} =x^{a-b}\\ x^{-a} = \frac{1}{x^a} \\ \\ \frac{b^{-7}}{b^{-4}b^{-2}} =\frac{b^{-7}}{b^{-4+(-2)}} =\frac{b^{-7}}{b^{-6}} =b^{-7-(-6)}=b^{-7+6}=b^{-1}= \frac{1}{b} \\ b= - \frac{1}{5} \\ 1:(-\frac{1}{5})=- \frac{5}{1} =-5$