JAMB - Mathematics (1991 - No. 18)

Factorize 1 - (a - b)²

(1 - a - b)(1 - a + b)

(1 + a - b)(1 - a + b)

(1 - a + b)(1 - a + b)

(1 + a + b)(1 + a + b)

1 - (a - b)² = [1 + (a - b)][1 - a + b]

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