Question

Given that p + q + r = x and pq + qr + pr = y.
Which of these is equal to p2 + q2 + r2?

1 x2
2 x + y
3 x2 - 2y
4 x2 + 2y

Answer 1

Answer:

$x {}^{2} - 2y$

Step-by-step explanation:

$(p + q + r) {}^{2} = p {}^{2} + q {}^{2} + r {}^{2} + 2pq + 2qr + 2rp$

$putting$

p+q+r=x

pq+qr+rp=y

$then \: you \: get$

$p {}^{2} + q {}^{2} + r {}^{2} = x {}^{2} - 2y$