Question

Упростите выражение!​

Answer 1

$( \frac{1}{a} + \frac{1}{b} ) \div ( \frac{ {a}^{2} + 2ab + {b}^{2} }{2ab} ) = \\ = \frac{a + b}{ab} \times \frac{2ab}{(a + b)^{2} } = \frac{2}{a + b}$