2026-07-072026-07-07http://salesiana.dossiersoluciones.com/handle/123456789/221578Let a,b,c,d be nonzero rational numbers whose product is a square, and let V be the diagonal quartic surface in PP^3 defined by ax^4+by^4+cz^4+dw^4=0. We prove that if V contains a rational point that does not lie on any of the 48 lines on V or on any of the coordinate planes, then the set of rational points on V is dense in both the Zariski topology and the real analytic topology.added referenceAlgebraic GeometryNumber Theory11Dxx, 11Gxx, 14Gxx, 14Jxxtext