m=2
则-5x-5=0
x=-1
m≠2
a=m-2,b=-(m+3),c=-2m-1
△=b²-4ac=m²+6m+9+8m²-12m-8
=9m²-6m+1
=(3m-1)²
所以x=[(m+3)±(3m-1)]/2(m-2)
所以x1=-1,x2=(2m+1)/(m-2)