Question

Simplify: $(7a-6b+5c{)}^2$

Answer 1

Given: $(7a-6b+5c{)}^2$

Using identity $(x+y+z{)}^2=x^2+y^2+z^2+2(xy+yz+xz)$ we get,

$(7a-6b+5c{)}^2=(7a{)}^2+(-6b{)}^2+(5c{)}^2+2\left[\right(7a\left)\right(-6b)+(5c\left)\right(-6b)+(7a\left)\right(5c\left)\right]$

$=49a^2+36b^2+25c^2-84ab-60bc+70ac$

Hence, $(7a-6b+5c{)}^2=49a^2+36b^2+25c^2-84ab-60bc+70ac$