Lemma 1. The equation x4 −2y4=1 has only one nonnegative integer solution (x, y) = (1, 0). Lemma 2. The equation 2x4 − y4 = 1 has only one positive integer solution (x, y) = (1, 1)
Lemma 1. The equation x4−2y4=1 has only one nonnegative integer solution (x, y) = (1, 0).Lemma 2. The equation 2x4 − y4 = 1 has only one positive integer solution (x, y) = (1, 1)