Question

A expressão 4-a² / ( 2+a ) (2-a) . O a equivale a qual valor?

Answer 1

$\dfrac{4-a^{2}}{\left(2+a\right)\left(2-a\right)}=\dfrac{2^{2}-a^{2}}{\left(2+a\right)\left(2-a\right)}=\dfrac{\left(2+a\right)\left(2-a\right)}{\left(2+a\right)\left(2-a\right)}=1$