基本積分表

Preparing發表於2024-04-30

\(\int x^{\mu}dx=\frac{1}{\mu+1} x^{\mu+1}+C\)

\[\begin{eqnarray} \int x^{\mu}dx=\frac{1}{\mu+1} x^{\mu+1}+C \\ \mu 為常數, 但\mu \ne 0 \\ \\ 推導過程如下: \\ (\frac{1}{\mu+1} x^{\mu+1})' =\frac{(x^{\mu+1})' \cdot \mu +1 - x^{\mu+1} \cdot (\mu+1)'}{(\mu+1)^{2}} \\ \\ \because (\mu+1)'=0, \enspace (x^{\mu+1})'=(\mu+1) x^{\mu+1-1} \\ \\ \Rightarrow \frac{(\mu+1) x^{\mu} \cdot \mu +1 - x^{\mu+1} \cdot 0}{(\mu+1)^{2}} \\ \\ \frac{((\mu+1) x^{\mu} \cdot \mu +1}{(\mu+1)^{2}}=x^{\mu} \\ \\ (\frac{1}{\mu+1} x^{\mu+1})'=x^{\mu} \\ \\ \therefore \int x^{\mu}dx=\frac{1}{\mu+1} x^{\mu+1}+C \end{eqnarray} \]


\(\int a^{x}dx=\frac{a^{x}}{\ln{a}}+C\)

\[ \begin{eqnarray} \int a^{x}dx=\frac{a^{x}}{\ln{a}}+C, \enspace (a為常數,a>0,a \ne 1) \\ \\ 推導過程如下: \\ 已知: \enspace (a^{x})'=a^{x}\ln{a}, \enspace (\ln{a})'=0 \\ \\ \frac{(a^{x})'}{(\ln{a})'}=\frac{(a^{x})'\ln{a}-a^{x}(\ln{a})'}{\ln^{2}{a}} \\ \\ \frac{a^{x}\ln{a} \cdot \ln{a}-a^{x}\cdot 0}{\ln^{2}{a}} \\ \\ \Rightarrow \frac{a^{x}\ln{a} \cdot \ln{a}}{\ln^{2}{a}}=a^{x} \\ \\ \therefore \frac{a^{x}}{\ln{a}}之導為a^{x} \\ \\ \therefore \int a^{x}dx=\frac{a^{x}}{\ln{a}}+C , \enspace (a>0,a \ne 1) \end{eqnarray} \]


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