Question

(p+q+r) (p+q-r) +7pq​

Answer 1

Answer:

$p^{2}$ +  $q^{2}$ +  $r^{2}$  + 9pq + 2pr + 2rq

Step-by-step explanation:

(p+q+r) (p+q-r) +7pq​

= (p x p) + (p x q) + (p x r) +

  (q x p) + (q x q) + (q x r) +

  (r x p) + (r x q) + (r x r) + 7pq

= $p^{2}$+  pq + pr + qp + $q^{2}$ + qr + rp + rq + $r^{2}$ + 7pq

(by arranging like terms we get)

$p^{2}$ +  $q^{2}$ +  $r^{2}$ + (pq + qp + +7pq) + (pr + rp) + (rq + qr)

= $p^{2}$ +  $q^{2}$ +  $r^{2}$  + 9pq + 2pr + 2rq