Question

Write the following in the expanded form:

(ii) $(2a-3b-c{)}^2$

Answer 1

Given, $(2a-3b-c{)}^2$
Using Identity,
$(a+b+c{)}^2=a^2+b^2+c^2+2ab+2bc+2ca$
$\therefore (2a-3b-c{)}^2$
$=(2a{)}^2+(-3b{)}^2+(-c{)}^2+2\times 2a\times -3b+2\times -3b\times -c+2\times -c\times 2a$
$=4a^2+9b^2+c^2-12ab+6bc-4ac$

Hence, $(2a-3b-c{)}^2=4a^2+9b^2+c^2-12ab+6bc-4ac.$