Question

упростите выражение​

Answer 1

$( \frac{a}{a - 4} - \frac{a}{a + 4} ) \times \frac{a + 4}{a} = \frac{a(a + 4) - a(a - 4)}{(a + 4)(a - 4)} \times \frac{a + 4}{a} = \frac{a(a + 4) - a(a - 4)}{a(a - 4)} = \frac{a {}^{2} + 4a - a {}^{2} + 4a }{a(a - 4) } = \frac{8a}{a(a - 4)} = \frac{8}{a - 4}$