△=0 ⇒(p+q)2−4xpq2=0 ⇒p2+q2+2pq−2pq=0 ⇒p2+q2=0 ⇒p=0 and q=0 ⇒p+q=0
If the equation x2+px+q=0 and x2+qx+p=0 have exactly one root in common, then equation with other roots is
If every pair of the equations x2+px+qr=0 , x2+qx+rp=0 , x2+rx+pq=0 have a common root, then the sum of three common roots is