Question

ab^2 + ( a-1) b-1

I know how to solve but I have a confusion in the second step that how ab^2 ab -b-1....(in this how ab came.....please explain that)​

Answer 1

Step-by-step explanation:

ab^2+(a-1)(b-1)

ab^2+ab+a-b+1 (ab came by multiplying a and b in (a-1) and (b-1)

Answer 2

(a-1)b -1 become ab-b because b is multiplied to a-1