应该是
(ab+b)²-(a+1)
=b²(a+1)²-(a+1)
=(a+1)[b²(a+1)-1]
=(a+1)(ab²+b²-1)
还是
(ab+b)²-(a+1)²
=b²(a+1)²-(a+1)²
=(a+1)²(b²-1)
=(a+1)²(b-1)(b+1)
应该是
(ab+b)²-(a+1)
=b²(a+1)²-(a+1)
=(a+1)[b²(a+1)-1]
=(a+1)(ab²+b²-1)
还是
(ab+b)²-(a+1)²
=b²(a+1)²-(a+1)²
=(a+1)²(b²-1)
=(a+1)²(b-1)(b+1)