8.2)1)(4d+7)/7d - (d - 6)/6d = 6(4d+7)/7d·6 - 7(d - 6)/6d·7 = (24d+42)/42d - (7d - 42)/42d=(24d+42-7d+42)/42d=(17d+84)/42d
3)(6a+2)/ab - (2a+4)/a²b = a(6a+2)/a²b - (2a+4)/a²b = (6a²+2a)/a²b - (2a+4)/a²b = (6a²+2a-2a-4)/a²b = (6a²-4)/a³
5)1/x³-(1+x²)/x⁵=x²/x³·x²-(1+x²)/x⁵=x²/x³⁺²-(1+x²)/x⁵=(x²-1-x²)/x⁵=(0-1)/x⁵
8.4)1)a/(a-b)+a/b=ab/b(a-b)+a(a-b)/b(a-b)=(ab+a²-ab)/b(a-b)=a²/(ab-b²)
2)4/x-(5x+4)/(x+2)=4(x+2)/x(x+2)-x(5x+4)/x(x+2)=(4x+8-5x²-4x)/x(x+2)=(8-5x²)/ /(x²+2x)
3)b/(b-2)-2/(b+2)=b(b+2)/(b-2)(b+2)-2(b-2)/(b-2)(b+2)=(b²+2b-2b+4)/(b-2)(b+2)=(b²+4)/(b-2)(b+2)=(b+2)(b+(-2))/(b-2)(b+2)=(b+(-2))/(b-2)