\[(3x + 1)(3x - 1) + (5x + 1)^{2} =\]
\[= (3x)^{2} - 1 + 25x^{2} + 10x + 1 =\]
\[= 9x^{2} + 25x^{2} + 10x =\]
\[= 34x^{2} + 10x = 2x(17x + 5).\]