高数题,计算下列定积分? 40
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2021-11-27 · 知道合伙人教育行家
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(2)
∫(1->2) √(1+x) dx
=(2/3)[(1+x)^(3/2)]|(1->2)
=(2/3)[3^(3/2)- 2^(3/2)]
(8)
∫(1->e) xlnx dx
=(1/2)∫(1->e) lnx dx^2
=(1/2)[x^2.lnx]|(1->e) -(1/2)∫(1->e) x dx
=(1/2)e^2 -(1/4)[x^2]|(1->e)
=(1/2)e^2 -(1/4)(e^2-1)
=(1/4)(e^2+1)
(9)
∫(0->2π) xsinx dx
=-∫(0->2π) x dcosx
=-[xcosx]|(0->2π) +∫(0->2π) cosx dx
=-2π +[sinx]|(0->2π)
=-2π
∫(1->2) √(1+x) dx
=(2/3)[(1+x)^(3/2)]|(1->2)
=(2/3)[3^(3/2)- 2^(3/2)]
(8)
∫(1->e) xlnx dx
=(1/2)∫(1->e) lnx dx^2
=(1/2)[x^2.lnx]|(1->e) -(1/2)∫(1->e) x dx
=(1/2)e^2 -(1/4)[x^2]|(1->e)
=(1/2)e^2 -(1/4)(e^2-1)
=(1/4)(e^2+1)
(9)
∫(0->2π) xsinx dx
=-∫(0->2π) x dcosx
=-[xcosx]|(0->2π) +∫(0->2π) cosx dx
=-2π +[sinx]|(0->2π)
=-2π
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