Question

(X-30)[1500+400(40-X)]=17500 解这个方程.

Answer 1

(X-30)[1500+400(40-X)]=17500

(x-30)(17500-400x)=17500

(x-30)(175-4x)=175

175x-4x^2-5250+120x=175

4x^2-295x+5425=0

(4x-155)(x-35)=0

x1=155/4

x2=35