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