Анюта2600 1). x/7x=1/7
2). A). 1/a^2 + (a-2)/a = (1+a^2-2a)/a^2 = (a-1)^2/a^2
B). 4/(c^2-9) - 2/(c^2-3c) = 4/(c-3)(c+3) - 2/c(c-3) = (4c-2(c+3))/c(c-3)(c+3) = (4c-2c-6)/с(с-3)(с+3) = (2с-6)/с(с-3)(с+3) = 2(с-3)/с(с-3)(с+3) = 2/с(с+3) = 2/(с^2+3с)
4. 2у/(у-3) + у/(у+3) + 2у^2/(9-у^2) = (2у(у+3)+у(у-3)-2у^2)/(3+у)(у-3) = (2у^2+6у+у^2-3у-2у^2)/(3+у)(у-3) = (у^2+3у)/(3+у)(у-3) = (у(у+3)/(у-3)(3+у) = у/(у-3)