用分部积分法求下列不定积分,要有详细过程,谢谢了.
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用分部积分法求下列不定积分,要有详细过程,谢谢了.
用分部积分法求下列不定积分,要有详细过程,谢谢了.
用分部积分法求下列不定积分,要有详细过程,谢谢了.
(1)
∫xarctanx dx
=(1/2)∫arctanx d(x^2)
=(1/2)x^2.arctanx -(1/2)∫x^2/(1+x^2) dx
=(1/2)x^2.arctanx -(1/2)∫dx + (1/2)∫dx /(1+x^2)
=(1/2)x^2.arctanx -(1/2)x + (1/2)arctanx + C
(...
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(1)
∫xarctanx dx
=(1/2)∫arctanx d(x^2)
=(1/2)x^2.arctanx -(1/2)∫x^2/(1+x^2) dx
=(1/2)x^2.arctanx -(1/2)∫dx + (1/2)∫dx /(1+x^2)
=(1/2)x^2.arctanx -(1/2)x + (1/2)arctanx + C
(3)
∫ (secx)^3dx=∫ secxdtanx
= secx.tanx - ∫ (tanx)^2.secx dx
= secx.tanx - ∫ [(secx)^2-1].secx dx
2∫ (secx)^3dx =secx.tanx + ∫ secx dx
=secx.tanx + ln|secx+tanx|
∫ (secx)^3dx = (1/2) [secx.tanx + ln|secx+tanx|] + C
(5)
∫xln(x^2+1) dx
=(1/2)∫ln(x^2+1) d(x^2)
=(1/2)x^2.ln(x^2+1) - ∫x^3/(x^2+1) dx
=(1/2)x^2.ln(x^2+1) - ∫ [x(x^2+1) -x ]/(x^2+1) dx
=(1/2)x^2.ln(x^2+1) - ∫ xdx + (1/2)∫ 2x/(x^2+1) dx
=(1/2)x^2.ln(x^2+1) - (1/2) x^2 + (1/2)ln|x^2+1| + C
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