Question

Expand each of the following using suitable identities:

a) (a + 3b + c)²​

PLEASE DO IT ON A ROUGH PAGE. ​

Answer 1

We have, (2a−3b−c)²

Using identity

(a+b+c) 2 =a² +b² +c²+2ab+2bc+2ca,

we get

∴(2a−3b−c)²

=(2a)²+(−3b)²+(−c)² +2(2a)(−3b)+2(−3b)(−c)+2(−c)2a

=4a²+9b²+c²-12ab+6bc-4ac