已知x1+x2=-3m/2 ,x1*x2=3m^2-4/4
问题描述:
已知x1+x2=-3m/2 ,x1*x2=3m^2-4/4
如何求x1-x2的值?
那√2*|x1-x2| 会等于多少啊?
答
x1+x2=-3m/2
平方
x1²+x2²+2x1x2=9m²/4
x1²+x2²=9m²/4-2(3m²-4)/4=(3m²+8)/4
(x1-x2)²
=x1²+x2²-2x1x2
=(3m²+8)/4+(3m²-8)/4
=6m²/4
所以x1-x2=±m√6/2