4 2 1 + x - x
2 / 2\ 1 + x *\-1 + x /
/ ___\ / ___\ / ___ \ / ___\ | I \/ 3 | | I \/ 3 | | \/ 3 I| | I \/ 3 | |x + - + -----|*|x + - - + -----|*|x + - ----- + -|*|x + - - - -----| \ 2 2 / \ 2 2 / \ 2 2/ \ 2 2 /