有绝对值,面积全在x轴上面,没可能是负数!答案是1.∫[1,3] |x-2|dx = |∫[1,2] (x-2)dx + ∫[2,3] (-x+2)dx|= |(x²/2-2x)[1,2] + (-x²/2+2x)[2,3]|= |[(4/2-4)-(1/2-2)] + [(-9/2+6)-(-4/2+4)]|= |-0.5 + (...