(i) (3p + q) (3p + r)
Substitute x = 3p, a = q and b = r in
(x + a) (x + b) = x2 + x(a + b) + ab
(3p + q)(3p + r) = (3p)2 + 3p (q + r) + (q x r)
= 32 p2 + 3p(q + r) + qr
(3p + q)(3p + r) = 9p2 + 3p(q + r) + qr
(ii) (3p + q) (3p – q)
Substitute a = 3p and b = q in
(a + b) (a – b) = a2 – b2, we have
(3p + q) (3p – q) = (3p)2 – q2
= 32 p2 – q2
(3P + q) (3p – q) = 9p2 – q2
