Multiply the binomials.
(i)(2x + 5) and(4x − 3) (ii) (y − 8) and (3y −4)
(iii)(2.5l −0.5m) and (2.5l + 0.5m)
(iv) (a + 3b)and (x + 5)
(v)(2pq + 3q2)and (3pq − 2q2)
(vi)(34a2+3b2) and 4(a2−23b2)
(i)(2x + 5) ×(4x − 3) = 2x ×(4x − 3) + 5 ×(4x − 3)
=8x2 − 6x + 20x − 15
= 8x2 + 14x −15(By adding liketerms)
(ii)(y −8) × (3y − 4) =y × (3y −4) − 8 × (3y −4)
=3y2 − 4y − 24y + 32
=3y2 − 28y + 32 (By adding liketerms)
(iii)(2.5l −0.5m) × (2.5l + 0.5m)= 2.5l × (2.5l+ 0.5m) − 0.5m (2.5l + 0.5m)
=6.25l2 + 1.25lm − 1.25lm −0.25m2
=6.25l2 − 0.25m2
(iv)(a + 3b)× (x + 5) = a× (x + 5) + 3b× (x + 5)
= ax + 5a + 3bx + 15b
(v)(2pq + 3q2)× (3pq − 2q2)= 2pq × (3pq −2q2) + 3q2 ×(3pq − 2q2)
=6p2q2 − 4pq3+ 9pq3 − 6q4
=6p2q2 + 5pq3 −6q4
(vi) Given (34a2+3b2) and 4(a2−23b2)
⇒(34a2+3b2)×4(a2−23b2)=34a2[4(a2−23b2)+3b2[4(a2−23b2]
=3a2(a2−23b2)+12b2(a2−23b2)
=3a4−2a2b2+12a2b2−8b4
=3a4+10a2b2−8b4