2 2 49*x - 121*y
49*x^2 - 121*y^2
/ 11*y\ / 11*y\ 1*|x + ----|*|x - ----| \ 7 / \ 7 /
(1*(x + 11*y/7))*(x - 11*y/7)
(-11*y + 7*x)*(7*x + 11*y)
49.0*x^2 - 121.0*y^2