From a point P, perpendiculars PM and PN are drawn to x and y axes, respectively. If MN passes through fixed point (a,b), then locus of P is

Let Ph,kSo, points M and N are h,0 and 0,k, respectively.MN passes through the point Qa,b∴  So, M,N and Q are collinear.∴   −kh=b−0a−h∴     ak−hk=−bhso locus is bx+ay=xy