求不定积分的题，，想要过程，谢谢

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令x=tant,dx=sec²tdt
原式=∫滑蠢(tant+1)/sect*sec²慧粗tdt
=∫(tant+1)sectdt
=∫sect*tantdt+∫sectdt
=sect+ln|sect+tant|+C
=√(x²+1)+ln|√(x²+1)+x|+C
sint=xcost,(x²+1)cos²t=1
sec²t=1/cos²前让镇t=x²+1
sect=√(x²+1)

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