(x+3)(x+m)=x^2+kx-15 则k+m=
问题描述:
(x+3)(x+m)=x^2+kx-15 则k+m=
答
k=-2 m=-5
答
(x+3)(x+m)=x^2+kx-15
拆分 :x^2+xm+3x+3m=x^2=kx-15
两边同去掉x^2:x(m+3)+3m=kx-15
所以:x(m+3)=kx m+3=k
3m=-15 m=-5
k=-2
k+m=-7
懂了吗?