（m²+m)(x+2)=6x+m+15
(m²+m-6)x=-2(m²+m)+m+15
(m²+m-6)x=-2m²-m+15
因为无解,所以
m²+m-6=0,而-2m²-m+15≠0
(m-2)(m+3)=0,(-2m+5)(m+3)≠0
所以
m=2