Standard Integrals and Linear Composites

Standard Integrals and Linear Composites

IB Year 6 | Grade 12

If \(\mathrm{F}\prime(x)=\mathrm{f}(x)\), then a linear inner function contributes a constant scale factor:

\(\int\mathrm{f}(ax+b)\,\mathrm{d}x=\dfrac{1}{a}\mathrm{F}(ax+b)+C\qquad(a\ne0)\)

IntegrandAntiderivative
\((ax+b)^n\)\(\dfrac{(ax+b)^{n+1}}{a(n+1)}+C\)
\(\dfrac{1}{ax+b}\)\(\dfrac{1}{a}\ln|ax+b|+C\)
\(e^{ax+b}\)\(\dfrac{1}{a} e^{ax+b}+C\)
\(\sin(ax+b)\)\(-\dfrac{1}{a}\cos(ax+b)+C\)
\(\cos(ax+b)\)\(\dfrac{1}{a}\sin(ax+b)+C\)
\(\sec^2(ax+b)\)\(\dfrac{1}{a}\tan(ax+b)+C\)
\(\operatorname{cosec}^2(ax+b)\)\(-\dfrac{1}{a}\cot(ax+b)+C\)

In the power rule, \(n\in\mathbb Q\) and \(n\ne-1\); choose a real interval on which the expression is defined. The reciprocal form requires \(ax+b\ne0\). Trigonometric denominators must also be non-zero.

If \(\mathrm{F}\prime(x)=2x\) and \(\mathrm{F}(1)=5\), then \(\mathrm{F}(x)=x^2+C\), \(C=4\), and \(\mathrm{F}(x)=x^2+4\).

Dividing by a constant works only for a linear inner function. For \(\int\dfrac{1}{3x^2-1}\,\mathrm{d}x\), the inner derivative is \(6x\), so use another technique.

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