∵方程2x²+3x-1=0的两根为x1、x2
∴由根与系数关系得
x1+x2=-3/2 ①
x1x2=-1/2 ②
∵1/x1+1/x2=(x1+x2)/ x1x2 ③
∴将①②代入③得
1/x1+1/x2=(x1+x2)/ x1x2 =（-3/2 ）/(-1/2 )=3