如果純碎是求該圖形的面積而不是該定積分的值的話,就要加上絕對值了,因為面積是大于0的.
令y = x(x - 1)(x - 2) = 0
--> x = 0、x = 1、x = 2
所以面積 = ∫[0→2] |y| dx
= ∫[0→2] |x(x - 1)(x - 2)| dx
= ∫[0→1] x(x - 1)(x - 2) dx - ∫[1→2] x(x - 1)(x - 2) dx
= {1/4} - {- 1/4}
= 1/2