Find the product.
(i) (5−2x)(3+x) (ii) (x+7y)(7x−y)
(iii) (a2+b)(a+b2) (iv) (p2−q2)(2p+q)
(i)Given (5−2x)(3+x)=5(3+x)−2x(3+x)=15+5x-6x-2x^2\therefore (5 − 2x)(3 + x)=-2x^2-x+15$
(ii) Given (x+7y)(7x−y)=x(7x−y)+7y(7x−y)
=7x2−xy+49xy−7y2
∴(x+7y)(7x−y)=7x2+48xy−7y2
(iii) Given (a2+b)(a+b2)=a2(a+b2)+b(a+b2)
∴(a2+b)(a+b2)=a3+a2b2+ab+b3
(iv) Given (p2−q2)(2p+q)=p2(2p+q)−q2(2p+q)
∴(p2−q2)(2p+q)=2p3+p2q−2pq2−q3