Question

СРОЧНО 20 БАЛЛОВ ЗА ОДНО ЗАДАНИЕ

Answer 1

1 задание :

$1)\frac{x+3}{6x-30}*\frac{450}{x^{2}+3x}=\frac{x+3}{6(x-5)}*\frac{450}{x(x+3)}=\frac{75}{x(x-5)}\\\\2)\frac{3x}{x-5}-\frac{75}{x(x-5)}=\frac{3x^{2}-75}{x(x-5)}=\frac{3(x^{2}-25)}{x(x-5)}=\frac{3(x-5)(x+5)}{x(x-5)}=\frac{3x+15}{x}\\\\Otvet:\boxed{\frac{3x+15}{x}}$

2 задание :

$1)\frac{a-5}{a+5}-\frac{a+5}{a-5}=\frac{(a-5)^{2}-(a+5)^{2}}{(a-5)(a+5)}=\frac{a^{2}-10a+25-a^{2}-10a-25}{(a-5)(a+5)}=\frac{-20a}{(a-5)(a+5)}\\\\2)-\frac{20a}{(a-5)(a+5)}:\frac{5a}{25-a^{2}}=\frac{20a}{(a-5)(a+5)}*\frac{(a-5)(a+5)}{5a}=4\\\\Otvet:\boxed{4}$