4k 2+ 12 1 is a complete square number. 4k 2 is a complete square number, liuking 123.
Because 4k 2+4k+1= (2k+1) 2 is equal to121= 4k+1k = 30.
Liu Jin 123
(2n+ 15)^2=
4k^2+ 12 1=372 1=6 1^2
2n+ 15 = 6 1 . n = 23 . Liu king 123