An Application of Fermat's Method of Descent to a Real Quadratic Field
Yongliang Wang · Jiangnan daxue xuebao. Ziran kexue ban · 2009
Based on algebraic number theory and Fermat's method of descent,all solutions of an important Diophantine equation are determined in a real quadratic field,which implies that the Fermat equation has no non-trivial solutions in this ring for n=4.