20/(x-20)=(2x-40)/(x+40)
问题描述:
20/(x-20)=(2x-40)/(x+40)
答
两边除以2
10/(x-20)=(x-20)/(x+40)
两边乘(x-20)(x+40)
x²-40x+400=10x+400
x²-50x=0
x(x-50)=0
x=0,x=50