А) 1/(x²) +(x-2)/x=( 1+x²-2x)/x²=(x-1)²/x²=(1-1/x)²
б) 3/(x+y)+5/(x-y)=(3x-3y+5x+5y)/(x²-y²)=(8x+2y)/(x²-y²)=2(4x+y)/(x²-y²)
в)(1-5d²) /(d^6)-(d-5)/(d^4)+1/(d³)=(1-5d²) /(d^6)-(d-5)·d²/(d^6)+d³/(d^6)=
=(1-5d²) -(d-5)·d²+d³)/(d^6)=(1-5d² -d³+5d²+d³)/(d^6)=1/d^6=d^(-6)
г) 5c/(6c-6)-4c/(3c+3)+c²/(2c²-2)=(5c·(c+1)-4c·2(c-1)+3c²)/(6(c²-1))=
=(5c²+5c-8c²+8c+3c²)/(6(c²-1))=13c/(6(c²-1))