Computing an integral almost always means recognising an antiderivative. It is therefore worth keeping in mind a small table of elementary antiderivatives, obtained simply by “reading the differentiation rules backwards”. The additive constant CC reminds us that the antiderivative is defined up to a constant (the indefinite integral).

In brief — Elementary antiderivatives

f(x)f(x)P(f)\mathcal{P}(f)f(x)f(x)P(f)\mathcal{P}(f)
xnx^n (n1n\ne-1)xn+1n+1+C\dfrac{x^{n+1}}{n+1}+Ccosx\cos xsinx+C\sin x + C
11x+Cx+Csinx\sin xcosx+C-\cos x + C
1x\dfrac{1}{x}$\lnx+ C$
11+x2\dfrac{1}{1+x^2}arctanx+C\arctan x + C1cos2x\dfrac{1}{\cos^2 x}tanx+C\tan x + C
11x2\dfrac{1}{\sqrt{1-x^2}}arcsinx+C\arcsin x + C

The antiderivative is linear: P(αf+βg)=αP(f)+βP(g)\mathcal{P}(\alpha f+\beta g) = \alpha\,\mathcal{P}(f)+\beta\,\mathcal{P}(g).

Thanks to linearity, an integral of a combination of functions splits into the sum of the individual integrals, each solvable with the table.

Topics: Integral
Concepts: Indefinite integral · Linearity of the integral · Antiderivative
Skills: Integrating · Using formulae