Question

$(a+b-\frac{2ab}{a+b} )*\frac{a^{2}-b^{2} }{a^{2}+b^{2} }$

Answer 1

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

Ответ: а - b