If one root of the equations x2+px+q=0 and x2+αx+β=0 is common, then its value will be ( where p ≠ α and q ≠ β )
q−βα−p or pβ−αqq−β
Let the common root be y, then y2+py+q=0 and y2+αy+β=0
On solving by cross multiplication, we have
y2pβ−qα=yq−β=1α−p
∴ y=q−βα−p and y2y=y=pβ−qαq−β