Сократите дробь:
а) $\frac{x^2 - 9}{3x + 9}$;
б) $\frac{y^2 - 144}{12y - y^2}$;
в) $\frac{4 - d^2}{3d + 6}$;
г) $\frac{c^2 - 5c}{25 - c^2}$.
$\frac{x^2 - 9}{3x + 9} = \frac{x^2 - 3^2}{3(x + 3)} = \frac{(x - 3)(x + 3)}{3(x + 3)} = \frac{x - 3}{3}$
$\frac{y^2 - 144}{12y - y^2} = \frac{y^2 - 12^2}{y(12 - y)} = -\frac{(y - 12)(y + 12)}{y(y - 12)} = -\frac{y + 12}{y}$
$\frac{4 - d^2}{3d + 6} = \frac{2^2 - d^2}{3(d + 2)} = \frac{(2 - d)(2 + d)}{3(2 + d)} = \frac{2 - d}{3}$
$\frac{c^2 - 5c}{25 - c^2} = \frac{c(c - 5)}{5^2 - c^2} = \frac{c(c - 5)}{(5 - c)(5 + c)} = -\frac{c(c - 5)}{(c - 5)(c + 5)} = -\frac{c}{c + 5}$
Пожауйста, оцените решение
