integral from a to r of r^2

解答

\int_{a}^{r} r^{2} d r

\frac{r ^{3} - a ^{3}}{3}

求解步骤

\int_{a}^{r} r^{2} d r

使用幂法则

= [\frac{r ^{3}}{3}]_{a}^{r}

带入上下限计算后得:

\frac{r ^{3}}{3} - \frac{a ^{3}}{3}

= \frac{r ^{3}}{3} - \frac{a ^{3}}{3}

化简

= \frac{r ^{3} - a ^{3}}{3}

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