Integration of Power Functions

Integration of Power Functions

\(\int x^n\,\mathrm dx=\dfrac{x^{n+1}}{n+1}+C\qquad n\ne-1\)

\(\int(ax+b)^n\,\mathrm dx=\dfrac{(ax+b)^{n+1}}{a(n+1)}+C\qquad a\ne0,\ n\ne-1\)

The second formula requires a linear inner function. It does not apply directly to \(\int(x^2+1)^5\,\mathrm{d}x\).

Example

Integrate \(6x^2-1\) with respect to \(x\).

\(\int(6x^2-1)\,\mathrm{d}x\)\({}=6\left(\dfrac{x^3}{3}\right)-x+C\)\({}=2x^3-x+C\)

Integrate \((2x+1)^5\) with respect to \(x\).

\(\int(2x+1)^5\,\mathrm{d}x\)\({}=\dfrac{(2x+1)^6}{2(6)}+C\)\({}=\dfrac{(2x+1)^6}{12}+C\)

Integrate \(x^4-2x^3+1\) with respect to \(x\).

\(\int(x^4-2x^3+1)\,\mathrm{d}x\)\({}=\dfrac{x^5}{5}-2\left(\dfrac{x^4}{4}\right)+x+C\)\({}=\dfrac{x^5}{5}-\dfrac{x^4}{2}+x+C\)

Use intervals where the integrand is real and defined. If a = 0, integrate the resulting constant. Check by differentiating and include the integration constant.

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Answer:\(\displaystyle\int x^n\,\mathrm{d}x=\dfrac{x^{n+1}}{n+1}+C\) for \(n\ne-1\), and \(\displaystyle\int(ax+b)^n\,\mathrm{d}x=\dfrac{(ax+b)^{n+1}}{a(n+1)}+C\) for \(a\ne0\) and \(n\ne-1\)

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