Question

помогите с алгеброй

Answer 1

Объяснение:

$( \frac{a}{b} - \frac{b}{a} ) \times \frac{1}{a - b} = \frac{ {a}^{2} - {b}^{2} }{ab} \times \frac{1}{a - b} = \frac{(a - b)(a + b)}{ab} \times \frac{1}{a - b} = \frac{a + b}{ab} \\ \frac{a + b}{ab} = \frac{ \frac{1}{7} + \frac{1}{9} }{ \frac{1}{7} \times \frac{1}{9} } = \frac{ \frac{9 + 7}{63} }{ \frac{1}{63} } = \frac{16}{63} \div \frac{1}{63} = \frac{16}{63} \times \frac{63}{1} = 16$