x/(x-2)=(x-4)/(x-5)
方程两边同乘(x-2)(x-5),得:
x(x-5)=(x-4)(x-2)
x^2-5x=x^2-6x+8
x=8
x/(x-3)=(x+1)/(x-1)
x^2-x=x^2-2x-3
x=-3