Question

qual o valor da expressão a + b /1 - a.b para a = - 1 e b = 3

Answer 1

Boa noite Fabricio!
Solução!

$a=-1\\\\\ b=3\\\\\ \dfrac{a+b}{1-a.b} \\\\\\\\ \dfrac{-1+3}{1-(-1).(3)}\\\\\\\ \dfrac{-1+3}{1-(-3)}\\\\\\\ \dfrac{-1+3}{1+3}\\\\\\\ \frac{2}{4}\\\\\\\ \frac{1}{2}$

$\boxed{Resposta: \dfrac{1}{2}}$

Boa noite!
Bons estudos!

Answer 2

Basta substituir os valores indicados nas respectivas incógnitas:


$\dfrac{a+b}{1-ab} \\\\\\Para:~~~~ a=-1~~~e~~~b=3\\\\\\ \dfrac{-1+3}{1-(-1)*3}\to~~~ \dfrac{2}{1-(-3)}\to~~~\dfrac{2}{1+3}\to~~~ \dfrac{2}{4} \to~~~ \large\boxed{~ \frac{1}{2} ~}$