两边除以4(x-20)(x-13)=36x²-33x+260=36x²-33x+224=0求根公式x=(33±√193)/2
童鞋，你题目有没有错呀？-（-26+2x）（40-2x）=144-{[（-26）*40]-(2x)^2}=1444x^2+26*40=1444x^2=144/(26*40)x^2=144/(26*40*4)x=√[144/(26*40*4)]
