1.已知a,b是方程2x²-3x-1=0两根,求a-b=?,与b²/a=?
∵a+b=3/2 (a+b)²=9/4
ab=-1/2
(a-b)²=(a+b)²-4ab
=9/4-4(-1/2)
=9/4+2
=17/4
|a-b|=√17/2
其他提问对吗?