Question

выполните вычитание 3/x+y-3/x-y

Answer 1

$\frac{3}{x + y} - \frac{3}{x - y} = 3 \times ( \frac{1}{x + y} - \frac{1}{x - y} ) = 3 \times ( \frac{x - y - (x + y)}{(x + y)(x - y)} ) = \\ \\ = 3 \times ( \frac{x - y - x - y}{ {x}^{2} - {y}^{2} } )= 3 \times \frac{ - 2y}{ {x}^{2} - {y}^{2} } = - \frac{6y}{ {x}^{2} - {y}^{2} }$