4.3
а)(2+t/t+1)*3t²+3t/12t+8=3t+2/t+1*3t(t+1)/4(3t+2)=3t/4
б)z-3/z+3*(z+z²/3-z)=z-3/z+3*3z-z²+z²/3-z=z-3/z+3*(-3z/z-3)=-3z/z+3
4.4
a)(6/x-y-5/x+y)*x-y/x+11y=6x+6x-5x+5y/(x-y)(x+y)*x-y/x+11y=x+11y/(x-y)(x+y)*x-y/x+11y=1/x+y
в)(x-2y/xy+1/x)*x²y²/x-y=x²-2xy+xy/x²y*x²y²/x-y=x(x-y)/x²y*x²y²/x-y=x/y