acos(2*x + 6)
-2 ------------------- ________________ / 2 \/ 1 - (2*x + 6)
-8*(3 + x) ------------------- 3/2 / 2\ \1 - 4*(3 + x) /
/ 2 \ | 12*(3 + x) | -8*|1 + --------------| | 2| \ 1 - 4*(3 + x) / ----------------------- 3/2 / 2\ \1 - 4*(3 + x) /