计算定积分:∫(3,-4)|x|dx ∫(e+1,2)1/(x-1)dx ∫(8,-1)³√xdx

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计算定积分:∫(3,-4)|x|dx ∫(e+1,2)1/(x-1)dx ∫(8,-1)³√xdx

计算定积分:∫(3,-4)|x|dx ∫(e+1,2)1/(x-1)dx ∫(8,-1)³√xdx
计算定积分:∫(3,-4)|x|dx ∫(e+1,2)1/(x-1)dx ∫(8,-1)³√xdx

计算定积分:∫(3,-4)|x|dx ∫(e+1,2)1/(x-1)dx ∫(8,-1)³√xdx
∫(-3->4) |x| dx,所求面积都在x轴上面,所以要分区间
= ∫(-3->0) (-x) dx + ∫(0->4) x dx
= -x²/2 + x²/2
= -(-9/2) + 16/2
= 25/2
∫(2->e+1) 1/(x-1) dx
= ln|x-1|
= ln(e+1-1) - ln(2-1)
= lne - ln1
= 1
∫(-1->8) ∛x dx
= x^(1/3+1) / (1/3+1)
= (3/4)x^(4/3)
= (3/4)*8^(4/3) - (3/4)*(-1)^(4/3)
= 12 - 3/4
= 45/4

1.∫(ln^3x/x)dx =∫ln^3xdlnx =ln^4x/4 C
2.∫[(sin1/x)/x^2]dx =-∫sin1/xd(1/x)=cos(1/x) c
3.∫[(x-1)e^x]dx=∫xe^xdx-∫e^xdx=[xe^x-∫e^xdx]-∫e^xdx=(x-2)e^x c
4.∫(x^2lnx)dx=1/3∫lnxdx^3=1/3(x^3lnx-∫x^3dlnx)=1/3(x^3lnx-∫x^2dx)=1/3(x^3lnx-x^3/3 c)
=x^3(3lnx-1)/9 c