a, (2x - $3^{2}$) = 16
2x - 9 = 16
2x = 16 + 9
2x = 25
x = 25 : 2
x = $\frac{25}{2}$ = 12,5
Vậy x = 12,5
b, $(3x - 2)^{5}$ = -243
$(3x - 2)^{5}$ = $(-3)^{5}$
⇒ 3x - 2 = -3
3x = (-3) + 2
3x = -1
x = (-1) : 3
x = $\frac{-1}{3}$
Vậy x = $\frac{-1}{3}$
c, 63 . $3^{x-2}$ + 2 . $3^{x}$ = 27
63 . $3^{x}$ : $3^{2}$ + 2 . $3^{x}$ = 27
$3^{x}$ . (63 : $3^{2}$ + 2) = 27
$3^{x}$ . ( 63 : 9 + 2) = 27
$3^{x}$ . ( 7 + 2) = 27
$3^{x}$ . 9 = 27
$3^{x}$ = 27 : 9
$3^{x}$ = 3
$3^{x}$ = $3^{1}$
Vậy x = 1
d, $7^{x+1}$ + 14 . $7^{x-1}$ = 63
$7^{x}$ . 7 + 14 . $7^{x}$ : 7 = 63
$7^{x}$ . (7 + 14 : 7) = 63
$7^{x}$ . (7 + 2) = 63
$7^{x}$ . 9 = 63
$7^{x}$ = 63 : 9
$7^{x}$ = 7
$7^{x}$ = $7^{1}$
Vậy x = 1
