Question

P^2 + q^2 + r^2 = 138

pq+qr+rp = 3

Find p+q+r

Answer 1

p+q+r = 12

Explanation:

(p+q+r)^2 = p^2 + 2pq + 2pr + q^2 + 2qr + r^2

= p^2+q^2+r^2 + 2(pq+pr+qr)

so now we have

(p+q+r)^2 = 138 + 6