Б
8/(x-2)+(x²+2x+4)=(8+(x-2)(x²+2x+4))/(x-2)=(8+x³-8)/(x-2)=x³/(x-2)
в
(x-4y)/6x(x-y)-(x+4y)/6x(x+y)=[(x-4y)(x+y)-(x+4y)(x-y)]/[6x(x²-y²)]=
=(x²+xy-4xy-4y²-x²+xy-4xy+4y²)/[6x(x²-y²)]=-6xy/[6x(x²-y²)=y/(y²-x²)
г
(b+3)/9(b-3)-(b-1)/(b-3)(b+3)=[(b+3)²-9(b-1)]/[9(b²-9)]=
=(b²+6b+9-9b+9)/[9(b²-9)]=(b²-3b+18)/[9(b²-9)]