The three lines px+qy+r=0,qx+ry+p=0,rx+py+q=0 are concurrent if
p+q+r=0
p2+q2+r2=pq+qr+pr
p3+q3+r3=3pqr
None of these
Explanation for correct option:Given three lines are px+qy+r=0,qx+ry+p=0,rx+py+q=0The lines are concurrent if determinant is zero⇒pqrqrprpq=0⇒p(qr-p2)-q(q2-pr)+r(pq-r2)=0⇒pqr-p3-q3+pqr+pqr-r3=0⇒p3+q3+r3=3pqrHence option(C) is correct