已知方程4x²-7x-3=0,的两个根是x1,x2,-求x1-x2
问题描述:
已知方程4x²-7x-3=0,的两个根是x1,x2,-求x1-x2
答
(x1-x2)²
=x1²+x2²-2x1x2
=(x1+x2)²-4x1x2
=(7/4)²-4*(-3/4)
=49/16+3=
97/16
x1-x2=±√97/4