求1/(4+9x^2)的不定积分 求1/(4x^2+4x+5)的不定积分

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求1/(4+9x^2)的不定积分 求1/(4x^2+4x+5)的不定积分
求1/(4+9x^2)的不定积分 求1/(4x^2+4x+5)的不定积分

求1/(4+9x^2)的不定积分 求1/(4x^2+4x+5)的不定积分
详细解答如下,点击放大:

∫[1/(4+9x²)]dx:
令x=(2/3)tanθ,dx=(2/3)sec²θdθ
∫[1/(4+9x²)]dx
=∫{[(2/3)sec²θ]/4+9[(2/3)tanθ]²}dθ
=∫{[(2/3)sec²θ]/(4+4tan²θ)}dθ
=∫{[(2/3)sec²θ]...

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∫[1/(4+9x²)]dx:
令x=(2/3)tanθ,dx=(2/3)sec²θdθ
∫[1/(4+9x²)]dx
=∫{[(2/3)sec²θ]/4+9[(2/3)tanθ]²}dθ
=∫{[(2/3)sec²θ]/(4+4tan²θ)}dθ
=∫{[(2/3)sec²θ]/4sec²θ}dθ
=∫[(2/3)/4]dθ
=(1/6)θ+C ,∵x=(2/3)tanθ,θ=arctan(3x/2)
∴=(1/6)arctan(3x/2)

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