Question

(a^-1 + b^-1)/(ab)^-1

Answer 1

Hi friend,
$\frac{ \frac{1}{a}+ \frac{1}{b} }{ \frac{1}{ab} } = \frac{b+a}{ab} Xab=b+a$
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Answer 2

(1/a+1/b)/1/ab
{(b+a)ab}/1/ab
=>b+a