is
ex[x5 + 5x4 + 20x3 + 60x2 + 120x + 120] + C
ex[x5 - 5x4 - 20x3 - 60x2 - 120x - 120] + C
ex[x5 - 5x4 + 20x3 - 60x2 + 120x - 120] + C
ex[x5 + 5x4 + 20x3 - 60x2 - 120x + 120] + C
If f(x) = , then for any x 0, f(x) is equal to
1 - x2
1 + x2
B.