1/x1-1/x2=x2-x1/x1x2
(x2-x1)²=x2²+x1²+2x1x2-4x1x2=（x1+x2）²-4x1x2
根据伟达定理得
x1+x2=6
x1x2=3
故(x2-x1)²=6²-4X3=24
故x2-x1=±2√6
故1/x1-1/x2=（2-x1）/x1x2=±2√6/3
那个推荐答案是错的
=(x2-x1)/x1·x2
=[(x2+x1)^2+4·x1x2]/x1·x2
这错了x1+x2=6x1x2=3不对吧对着呢啊x1+x2=-b/ax1x2=c/a