Integrand size = 8, antiderivative size = 59 \[ \int x^2 \text {erfc}(b x) \, dx=-\frac {e^{-b^2 x^2}}{3 b^3 \sqrt {\pi }}-\frac {e^{-b^2 x^2} x^2}{3 b \sqrt {\pi }}+\frac {1}{3} x^3 \text {erfc}(b x) \]
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Time = 0.03 (sec) , antiderivative size = 59, normalized size of antiderivative = 1.00, number of steps used = 3, number of rules used = 3, \(\frac {\text {number of rules}}{\text {integrand size}}\) = 0.375, Rules used = {6497, 2243, 2240} \[ \int x^2 \text {erfc}(b x) \, dx=-\frac {x^2 e^{-b^2 x^2}}{3 \sqrt {\pi } b}-\frac {e^{-b^2 x^2}}{3 \sqrt {\pi } b^3}+\frac {1}{3} x^3 \text {erfc}(b x) \]
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Rule 2240
Rule 2243
Rule 6497
Rubi steps \begin{align*} \text {integral}& = \frac {1}{3} x^3 \text {erfc}(b x)+\frac {(2 b) \int e^{-b^2 x^2} x^3 \, dx}{3 \sqrt {\pi }} \\ & = -\frac {e^{-b^2 x^2} x^2}{3 b \sqrt {\pi }}+\frac {1}{3} x^3 \text {erfc}(b x)+\frac {2 \int e^{-b^2 x^2} x \, dx}{3 b \sqrt {\pi }} \\ & = -\frac {e^{-b^2 x^2}}{3 b^3 \sqrt {\pi }}-\frac {e^{-b^2 x^2} x^2}{3 b \sqrt {\pi }}+\frac {1}{3} x^3 \text {erfc}(b x) \\ \end{align*}
Time = 0.02 (sec) , antiderivative size = 42, normalized size of antiderivative = 0.71 \[ \int x^2 \text {erfc}(b x) \, dx=\frac {1}{3} \left (-\frac {e^{-b^2 x^2} \left (1+b^2 x^2\right )}{b^3 \sqrt {\pi }}+x^3 \text {erfc}(b x)\right ) \]
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Time = 0.41 (sec) , antiderivative size = 49, normalized size of antiderivative = 0.83
method | result | size |
parts | \(\frac {x^{3} \operatorname {erfc}\left (b x \right )}{3}+\frac {2 b \left (-\frac {x^{2} {\mathrm e}^{-b^{2} x^{2}}}{2 b^{2}}-\frac {{\mathrm e}^{-b^{2} x^{2}}}{2 b^{4}}\right )}{3 \sqrt {\pi }}\) | \(49\) |
parallelrisch | \(\frac {x^{3} \operatorname {erfc}\left (b x \right ) b^{3} \sqrt {\pi }-x^{2} {\mathrm e}^{-b^{2} x^{2}} b^{2}-{\mathrm e}^{-b^{2} x^{2}}}{3 b^{3} \sqrt {\pi }}\) | \(52\) |
derivativedivides | \(\frac {\frac {b^{3} x^{3} \operatorname {erfc}\left (b x \right )}{3}+\frac {-\frac {x^{2} {\mathrm e}^{-b^{2} x^{2}} b^{2}}{3}-\frac {{\mathrm e}^{-b^{2} x^{2}}}{3}}{\sqrt {\pi }}}{b^{3}}\) | \(54\) |
default | \(\frac {\frac {b^{3} x^{3} \operatorname {erfc}\left (b x \right )}{3}+\frac {-\frac {x^{2} {\mathrm e}^{-b^{2} x^{2}} b^{2}}{3}-\frac {{\mathrm e}^{-b^{2} x^{2}}}{3}}{\sqrt {\pi }}}{b^{3}}\) | \(54\) |
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Time = 0.24 (sec) , antiderivative size = 52, normalized size of antiderivative = 0.88 \[ \int x^2 \text {erfc}(b x) \, dx=-\frac {\pi b^{3} x^{3} \operatorname {erf}\left (b x\right ) - \pi b^{3} x^{3} + \sqrt {\pi } {\left (b^{2} x^{2} + 1\right )} e^{\left (-b^{2} x^{2}\right )}}{3 \, \pi b^{3}} \]
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Time = 0.19 (sec) , antiderivative size = 54, normalized size of antiderivative = 0.92 \[ \int x^2 \text {erfc}(b x) \, dx=\begin {cases} \frac {x^{3} \operatorname {erfc}{\left (b x \right )}}{3} - \frac {x^{2} e^{- b^{2} x^{2}}}{3 \sqrt {\pi } b} - \frac {e^{- b^{2} x^{2}}}{3 \sqrt {\pi } b^{3}} & \text {for}\: b \neq 0 \\\frac {x^{3}}{3} & \text {otherwise} \end {cases} \]
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Time = 0.20 (sec) , antiderivative size = 36, normalized size of antiderivative = 0.61 \[ \int x^2 \text {erfc}(b x) \, dx=\frac {1}{3} \, x^{3} \operatorname {erfc}\left (b x\right ) - \frac {{\left (b^{2} x^{2} + 1\right )} e^{\left (-b^{2} x^{2}\right )}}{3 \, \sqrt {\pi } b^{3}} \]
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Time = 0.29 (sec) , antiderivative size = 41, normalized size of antiderivative = 0.69 \[ \int x^2 \text {erfc}(b x) \, dx=-\frac {1}{3} \, x^{3} \operatorname {erf}\left (b x\right ) + \frac {1}{3} \, x^{3} - \frac {{\left (b^{2} x^{2} + 1\right )} e^{\left (-b^{2} x^{2}\right )}}{3 \, \sqrt {\pi } b^{3}} \]
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Time = 5.37 (sec) , antiderivative size = 50, normalized size of antiderivative = 0.85 \[ \int x^2 \text {erfc}(b x) \, dx=\frac {x^3\,\mathrm {erfc}\left (b\,x\right )}{3}-\frac {\frac {{\mathrm {e}}^{-b^2\,x^2}}{3\,\sqrt {\pi }}+\frac {b^2\,x^2\,{\mathrm {e}}^{-b^2\,x^2}}{3\,\sqrt {\pi }}}{b^3} \]
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