JAMB - Mathematics (1994 - No. 11)

Factorize a2x - b2y - b2x + a2y

(a - b)(x + y)

(y - x)(a - b)(a + b)

(x - y)(a - b)(a + b)

(x + y)(a - b)(a + b)

a2x - b2y - b2x + a2y = a2x - b2x - b2y + a2y Rearrange

= x(a2 - b2) + y(a2 - b2)

= (x + y)(a2 - b2)

= (x + y)(a + b)(a - b)