2 -7 + 3*x
-7 + 3*x^2
/ ____\ / ____\ | \/ 21 | | \/ 21 | |x + ------|*|x - ------| \ 3 / \ 3 /
(x + sqrt(21)/3)*(x - sqrt(21)/3)
-7.0 + 3.0*x^2