(100-2X)(X-30)=200的解

问题描述:

(100-2X)(X-30)=200的解

40

(100-2X)(X-30)=200
(x-50)(x-30)=-100
x^2-80x+1500=-100
x^2-80x+1600=0
(x-40)^2=0
x=40