Question

已知m，n是方程xx+2x-5=0的两个实数根，则mm-mn+3m+n的值为多少？要求有解的过程。

Answer 1

m、n为两个跟，则m+n=-2,mn=-5
mm-mn+3m+n
=mm+2m-5-mn+m+n+5
=0-(-5)+(-2)+5
=8

Answer 2

根据题意知　m²+2m-5=0
则：
m²+2m=5
m+n=-2
mn=-5

mm-mn+3m+n
=-mn+(m²+2m)+(m+n)
=-(-5)+5+(-2)
=8