(x-10)*(2x-10)*5=500

问题描述:

(x-10)*(2x-10)*5=500
f

(x-10)*(2x-10)=100 消去5
2x²-30x+100=100 展开
2x²-30x=0
2x(x-15)=0 提出2x
x1=0,x2=15