A) $2^{5x + 2}$ = $8^{9}$
$2^{5x + 2}$ = $(2³)^{9}$
$2^{5x + 2}$ = $2^{27}$
=> 5x + 2 = 27
5x = 27 - 2
5x = 25
x = 25 : 5
x = 5
B) $2^{x}$ = $4^{5}$ . $4^{3}$
$2^{x}$ = $4^{5 + 3}$
$2^{x}$ = $4^{8}$
$2^{x}$ = $(2²)^{8}$
$2^{x}$ = $2^{16}$
=> x = 16
Chúc học tốt!!!
