Question

Упростите выражение:

Answer 1

$frac{a + 3}{1 - a} times ( frac{a}{a - 3} - frac{a - 3}{a + 3} ) = \ frac{a + 3}{a - 3} times ( frac{9a - 9}{(a - 3)(a + 3)}) = \ frac{a + 3}{1 - a} times frac{3(a - 1)}{(a - 3)(a + 3)} = frac{3}{a - 3}$