Уростите выражение: 1)__a-5__+__12__a²-49a²-492)__2a-4__-__2b-4__a²-b²a²-b²3)__7a+5b__-4a+2b__(a-b)²(a-b)²4)__a²__-__2a-1__a²-1a²-1

[latex] \frac{a-5}{a^2-49}+ \frac{12}{a^2-49}= \frac{a-5+12}{(a-7)(a+7)} = \frac{a+7}{(a-7)(a+7)} = \frac{1}{a-7} [/latex] [latex] \frac{2a-4}{a^2-b^2}- \frac{2b-4}{a^2-b^2}= \frac{2a-4-2b+4}{(a-b)(a+b)}= \frac{2(a-b)}{(a-b)(a+b)}= \frac{2}{a+b} [/latex] [latex] \frac{7a+5b}{(a-b)^2} - \frac{4a+2b}{(a-b)^2}= \frac{7a+5b-4a-2b}{(a-b)^2}= \frac{3a+3b}{(a-b)^2}= \frac{3(a+b)}{a^2-2ab+b^2} [/latex] [latex] \frac{a^2}{a^2-1}- \frac{2a-1}{a^2-1}= \frac{a^2-2a+1}{(a-1)(a+1)}= \frac{(a-1)^2}{(a-1)(a+1)}= \frac{a-1}{a+1} [/latex]