Question

Se 2^(y-x) = A, então (0,25)^(x-y) vale:

a) A²
b) 2A
c) raiz quadrada de A
d) A+2
e) A/2

Answer 1

Vamos lá:  

$a=2^{y-x}\\ \\ (0,25)^{x-y}=(\frac{1}{4})^{-(y-x)}=(\frac{1}{2})^{-2(y-x)}=2^{2(y-x)}=(2^{y-x})^2=a^2$


Simples assim