ab+a+b+1=7
(a+1)(b+1)=7
分情况讨论.
a+1=7 b+1=1得a=6 b=0
a+1=1 b+1=7得a=0 b=6
a+1=-7 b+1=-1得a=-8 b=-2
a+1=-1 b+1=-7得a=-2 b=-8
所以a+b=6或-10