\[2c(1 + c) - (c - 2)(c + 4) =\]
\[= 2c + 2c^{2} - \ \left( c^{2} + 4c - 2c - 8 \right) =\]
\[= 2c + 2c^{2} - c^{2} - \ 2c + 8 = c^{2} + 8\]