∫(x3 - x, x, -1, 3) + ∫(1 - x3, x, 1, 3) + ∫(1 - x, x, 1, 3) + ∫(x, x, -1, 1)
= ∫(x3 - x, x, -1, 1) + ∫(x3 - x, x, 1, 3) + ∫(1 - x3, x, 1, 3) + ∫(1 - x, x, 1, 3) + ∫(x, x, -1, 1)
= 0 + ∫(x3 - x, x, 1, 3) + ∫(1 - x3, x, 1, 3) + ∫(1 - x, x, 1, 3) + 0
= ∫(x3 - x + 1 - x3 + 1 - x, x, 1, 3)
= ∫(2 - 2·x, x, 1, 3)
= [2·x - x2](1 bis 3)
= (2·3 - 32) - (2·1 - 12)
= -3 - (1)
= - 4