2 169 z - --- 196
z^2 - 169/196
/ 13\ / 13\ |x + --|*|x - --| \ 14/ \ 14/
(x + 13/14)*(x - 13/14)
2 -169 + 196*z ------------- 196
(-169 + 196*z^2)/196
-0.862244897959184 + z^2
(-13 + 14*z)*(13 + 14*z) ------------------------ 196
(-13 + 14*z)*(13 + 14*z)/196