Question

(3p-2q-5r)²+(3p+2q-5r)²

Answer 1

(3p-2q-5r)²+(3p+2q-5r)²

= { (3p-2q)^2 - 2.(3p-2q).5r + (5r)^2 } + { (3p+2q)^2 - 2.(3p+2q).5r + (5r)^2 }

= (9p^2 - 12pq + 4q^2 - 2.(3p-2q).5r + 25r^2) + (9p^2 + 12pq + 4q^2 - 2.(3p-2q).5r + 25r^2)

= 18p^2 + 8q^2 + 50r^2 - 20.(3p-2q).r