Question

437 (3,5) алгебра 7 класс СРОЧНО!!!! даю 30 баллов ​

Answer 1

Ответ:

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

$5) \frac{b - 1}{(b + 3) {}^{2}} - \frac{b}{b {}^{2} - 9 } = \frac{b - 1}{(b + 3 ){}^{2} } - \frac{b}{(b - 3)(b + 3)} = \frac{(b - 3)(b - 1) - b(b + 3)}{(b - 3)(b + 3) {}^{2} } = \frac{b {}^{2} - b - 3b + 3 - b {}^{2} - 3b }{(b - 3)(b {}^{2} + 6b + 9)} = \frac{ - 7b + 3}{b {}^{3} + 6b {}^{2} + 9b - 3b {}^{2} - 18b - 27 } = \frac{ - 7b + 3}{b {}^{3} + 3b {}^{2} - 9b - 27 }$