如果a,b是一元二次方程x2+3x-1=0的两个根 那么 |a-b|的值是
人气:488 ℃ 时间:2019-10-19 21:28:14
解答
x=a,x=b
则a+b=-3
ab=-1
所以(a-b)²
=(a+b)²-4ab
=9+4
=13
所以|a-b|=√13
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