$3$. $2^x = 4^5 . 16^2$
$⇔ 2^x = 2^{10} . 2^8$
$⇔ x = 18$
Vậy $x=18$
$6$. $2^x = 16^5 . 32^3$
$⇔ 2^x = 2^{20} . 2^{15}$
$⇔ x = 35$
Vậy $x=35$
$9$. $3^x = 9^{-6} : 27^{-5} . 81^8$
$⇔ 3^x = 3^{-12} : 3^{-15} . 3^{32}$
$⇔ x = 5$
Vậy $x=5$
$12$. $2^x = \dfrac{4^7}{4^3}$
$⇔ 2^x = 4^4$
$⇔ 2^x = 2^8$
$⇔ x = 8$
Vậy $x=8$
$15$. $3^x = \dfrac{9^4}{27^3}$
$⇔ 3^x = \dfrac{1}{3}$
$⇔ x = -1$
Vậy $x=-1$
$18$. $\dfrac{2^{x-3}}{4^{10}}= 8^3$
$⇔ 2^{x-3} = 2^{29}$
$⇔ x = 32$
Vậy $x=32$
$21$. $\dfrac{3^{x+5}}{9^3} = 27^4$
$⇔ 3^{x+5} = 3^{18}$
$⇔ x = 13$
Vậy $x=13$
$24$. $\dfrac{2^{2}}{2^x} = 2^{15}$
$⇔ 2^{2-x} = 2^{15}$
$⇔ x = -13$
Vậy $x=-13$
$27$. $\dfrac{2^3}{2^x} = 4^5$
$⇔ 2^{3-x} = 2^{10}$
$⇔ x = -7$
Vậy $x=-7$
$30$. $(-2)^x = 4^5 . 16^2$
$⇔ (-2)^x = 2^{18}$
$⇔ x = 18$
Vậy $x= 18$
$33$. $(-2)^x = -16^5.32^3$
$⇔ (-2)^x = -2^{20} . 2^{15}$
$⇔ (-2)^x = -2^{35}$
$⇔ x = 35$
Vậy $x=35$
$36. (-2)^x = - \dfrac{8^4}{2^3}$
$⇔ (-2)^x = - 2^9$
$⇔ x = 9$
Vậy $x=9$
$39$. $(-5)^x = \dfrac{25^{10}}{(-5)^{17}}$
$⇔ (-5)^x = - 5^3$
$⇔ x = 3$
Vậy $x=3$
