\[(3a - 2)(3a + 2) + (a + 8)(a - 8) =\]
\[= (3a)^{2} - 2^{2} + a^{2} - 8^{2} =\]
\[= 9a^{2} - 4 + a^{2} - 64 =\]
\[= 10a^{2} - 68.\]