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法1:I = (1/2)∫<4, 6>d(x^2-4)/(x^2-4)
= (1/2)[ln(x^2-4)]<4, 6> = (1/2)(ln32-ln12) = (1/2)ln(8/3)
法2:令 x = 2secu, 则 dx = 2secutanudu
I = ∫<arccos(1/2), arccos(1/3)> 2secu·2secutanudu/[4(tanu)^2]
= ∫<arccos(1/2), arccos(1/3)> (secu)^2du/tanu
= ∫<arccos(1/2), arccos(1/3)> dtanu/tanu
= [ln(tanu)]<arccos(1/2), arccos(1/3)> = ln2√2 - ln√3 = (1/2)ln(8/3)
= (1/2)[ln(x^2-4)]<4, 6> = (1/2)(ln32-ln12) = (1/2)ln(8/3)
法2:令 x = 2secu, 则 dx = 2secutanudu
I = ∫<arccos(1/2), arccos(1/3)> 2secu·2secutanudu/[4(tanu)^2]
= ∫<arccos(1/2), arccos(1/3)> (secu)^2du/tanu
= ∫<arccos(1/2), arccos(1/3)> dtanu/tanu
= [ln(tanu)]<arccos(1/2), arccos(1/3)> = ln2√2 - ln√3 = (1/2)ln(8/3)
追问
您好,,请问arccos(1/2), arccos(1/3中间的逗号是什么意思
追答
定积分从 arccos(1/2) 到 arccos(1/3)
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