Suppose $a(x) = 2x + 5 - 3x^2 + x^3$ and $b(x) = 4 - x^2 + 4x^4$. Find $(a\circ b)(3) - (b\circ a)(3).$
b(3) = 4 - 3^2 + 4(3)^4 = 319
a (b(3)) = a (319) = 2(319) + 5 - 3(319)^2 = -304640
a(3) = 2(3) + 5 - 3(3)^2 = -16
b(a(3)) = b(-16) = 4 - 16^2 + 4(16)^4 = 261892
a(b(3)) - b(a(3)) = -304640 - 261892 = -566532
+1725 
