如题所述
x²-5x-10=0
x1+x2=5
x1x2=-10
2.2x²+7x+1=0
x1+x2=-7/2
x1x2=1/2
3.3x²-1=2x+5
3x²-2x-6=0
x1+x2=2/3
x1x2=-2
4.x(x-1)=3x+7
x²-x=3x+7
x²-4x-7=0
x1+x2=4
x1x2=-7