Question

escontre o valor de a:
log2 ( a - 1) + log2 (a + 1)= 3

Answer 1

Resposta:

$\textsf{Leia abaixo}$

Explicação passo a passo:

$\mathsf{log_2\:(a - 1) + log_2\:(a + 1) = 3}$

$\mathsf{log_2\:(a - 1) + log_2\:(a + 1) = log_2\:2^3}$

$\mathsf{log_2\:(a - 1).(a + 1) = log_2\:8}$

$\mathsf{(a - 1).(a + 1) = 8}$

$\mathsf{a^2 - 1 = 8}$

$\mathsf{a^2 = 9}$

$\boxed{\boxed{\mathsf{a = 3}}}$