-2x^2-5x+1

问题描述:

-2x^2-5x+1

2x^2-5x+1=2(x^2-5x/2+1/2)=2[(x^2-5x/2+25/16)-25/16+1/2]=2[(x-5/4)^2-17/16]=2(x-5/4-√17/4)(x-5/4+√17/4)求好评