5(2x-10)(x-10)=300怎么解
问题描述:
5(2x-10)(x-10)=300怎么解
答
5(2x-10)(x-10)=300
(x-5)(x-10)=30
x^2-15x+50-30=0
x^2-15x+20=0
x=[15±√(225-80)]/2
=[15±√145]/2