Since α and β are the roots of the equation ax2+bx+c=0, then,
α+β=−ba
And,
αβ=ca
If the roots of any equation is αβ and βα, then,
(x−αβ)(x−βα)=0
x2−βαx−αβx+1=0
αβx2−x(α2+β2)+αβ=0
αβx2−x(α2+β2+2αβ−2αβ)+αβ=0
αβx2−x((α+β)2−2αβ)+αβ=0
cax2−x((−ba)2−2ca)+ca=0
cax2−x(b2a2−2ca)+ca=0
cax2−x(b2−2aca2)+ca=0
acx2−x(b2−2ac)+ac=0
Therefore, the required equation is acx2−x(b2−2ac)+ac=0.