@py
Bài làm :
$4^{x - 2}$ + $4^{x + 3}$ = 1040
⇔ $4^{x + 1}$ . $4^{- 3}$ + $4^{x + 1}$ = 1040
⇔ $4^{x + 1}$ . ( $4^{- 3}$ + 1 ) = 1040
⇔ $4^{x + 1}$ . $\dfrac{65}{64}$ = 1040
⇔ $4^{x + 1}$ = 1024
⇔ $4^{x + 1}$ = $4^{5}$
Ta có : x + 1 = 5
⇔ x = 4
Vậy x = 4
