积分1/(根号x+3次根号x)dx求解
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积分1/(根号x+3次根号x)dx求解
积分1/(根号x+3次根号x)dx求解
积分1/(根号x+3次根号x)dx求解
设x=t的6次方
∴t=6次根号下t
∫1/(t³+t²)dt的6次方
=∫6t的5次方/t²(t+1) dt
=∫6t³/(t+1)dt
=6∫(t³+1-1)/(t+1)dt
=6∫[t²-t+1 -1/(t+1)]dt
=6(t³/3-t²/2+t-ln|t+1|) +C
=2t³-3t²+6t-6ln|t+1|+C
=2√x-3(3次根号下x)+6(6次根号下x)-6ln(6次根号下x +1) +C
解 ∫1/(x^(1/2)+x^(1/3))dx
设t=x^(1/6),x=t^6
∫1/(t^3+t^2)d(t^6)
=6∫t^5/(t^3+t^2)dt
=6∫t^3/(t+1)dt
=6∫{t^2(t+1)-t^2}/(t+1)dt
=6∫t^2dt-6∫t^2/(t+1)dt
=...
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解 ∫1/(x^(1/2)+x^(1/3))dx
设t=x^(1/6),x=t^6
∫1/(t^3+t^2)d(t^6)
=6∫t^5/(t^3+t^2)dt
=6∫t^3/(t+1)dt
=6∫{t^2(t+1)-t^2}/(t+1)dt
=6∫t^2dt-6∫t^2/(t+1)dt
=2t^3-6∫{t(t+1)-t}/(t+1)dt
=2t^3-6∫tdt-6∫t/(t+1)dt
=2t^3-3t^2-6∫{t+1-1}/(t+1)dt
=2t^3-3t^2-6t+6ln|t+1|+c
把x带回去就好了
收起