Đáp án:
1/ $2^{x} = 4^{5} . 4^{3}$
$2^{x} = 4^{5+3}$
$2^{x} = 4^{8}$
$2^{x} = (2²)^{8}$
$2^{x} = 2^{16}$
Vậy $x = 16$
2/ $2^{x} = 4^{5} . 16^{2}$
$2^{x} = 4^{5} . (4²)²$
$2^{x} = 4^{5} . 4^{4}$
$2^{x} = 4^{5+4}$
$2^{x} = 4^{9}$
$2^{x} = (2²)^{9}$
$2^{x} = (2)^{18}$
Vậy $x = 18$
3/ $2^{x} = \dfrac{4^{7}}{4^{3}}$
$2^{x} = 4^{7} : 4^{3}$
$2^{x} = 4^{7-3}$
$2^{x} = 4^{4}$
$2^{x} = (2²)^{4}$
$2^{x} = (2)^{8}$
Vậy $x = 8$
4/ $(-5)^{x} = \dfrac{25}{-5}$
$(-5)^{x} = 25 : (-5)$
$(-5)^{x} = -5$
$(-5)^{x} = -5^{1}$
Vậy $x = 1$
