If α,β are the roots of ax2+bx+c=0 and α+k, β+k are the roots of px2+qx+r=0, then b2−4aca2−4pr is equal to
α+β=−ba, αβ=ca⇒[(α+k)+(β+k)2−4(α+k)(β+k)]=(α+β)2−4αβ⇒q2p2−4rp=b2a2−4ca⇒q2−4prp2=b2−4aca2⇒b2−4acq2−4pr=(ap)2