Question

o valor numérico da expressão a+b /1-ab' para a= 1/2 e b = 1/3, e :?

Answer 1

Temos:

$\dfrac{a+b}{1-ab}$

Logo:

$a+b = \frac{1}{2} + \frac{1}{3} = \frac{3*1 + 2*1}{2*3} = \frac{3+2}{6} = \boxed{ \frac{5}{6} } \\ \\ \\ 1 - ab = 1 - ( \frac{1}{2})*( \frac{1}{3}) = 1 - \frac{1*1}{2*3} = 1- \frac{1}{6} = \frac{6*1 - 1}{6} = \frac{6-1}{6} = \boxed{\frac{5}{6} }$

Assim:

$\dfrac{a+b}{1-ab} = \dfrac{ \frac{5}{6} }{ \frac{5}{6} } = \dfrac{5}{6} * \dfrac{6}{5} = \boxed{1}$