Question

Resolva 8ˣ⁻²=√128: (apresentar calculo) Urgenteeee!!!
a)1/4
b)13/6
c)-5/9
d)19/6
e)6/19

Answer 1

Resolução

$8 ^{x-2} = \sqrt{128}$
$2^{3(x-2)} = 128^{ \frac{1}{2} }$
$2 ^{3(x-2)} = 2 ^{7 . \frac{1}{2} }$
$2^{3x - 6} = 2 ^{ \frac{7}{2} }$
$3x - 6 = \frac{7}{2}$  -> multiplicação cruzada

$6x - 12= 7$
$6x = 7 + 12$
$6x = 19$
$x = \frac{19}{6}$