1,21c^6 - 9u^4 = (1,1c^3 - 3u^2)(1,1c^3 + 3u^2)
66^2 - 34^2 = 4356 - 1156 = 3200
7,7^2 - 2,3^2 = 59,29 - 5,29 = 54
75^2 - 4*37^2 = 5625 - 5476 = 149
1,21c^6 - 9u^4 = (1,1c^3 - 3u^2)(1,1c^3 + 3u^2)
66^2 - 34^2 = 4356 - 1156 = 3200
7,7^2 - 2,3^2 = 59,29 - 5,29 = 54
75^2 - 4*37^2 = 5625 - 5476 = 149