Question

15. Which of the following is true? *

ab - a - b + 1 = (1-a) (1-b)
ab - a - b + 1 = (a-1) (b-1)
ab - a - b + 1 = (1-a) (b-1)
ab - a - b + 1 = (a-1) (1-b)​

Answer 1

Answer:

ab - a - b + 1 = (a-1) (b-1) is true