10. Reduction Formulae
by M. Bourne
You may have noticed in the Table of Integrals that some integrals are given in terms of a simpler integral. These require a few steps to find the final answer.
Reduction formulae are integrals involving some variable `n`, as well as the usual `x`. They are normally obtained from using integration by parts.
We use the notation `I_n` when writing reduction formulae.
Example 1
Given the reduction formula
`I_n=intsin^nx\ dx` `=-1/ncos\ x\ sin^(n-1)x+(n-1)/nI_(n-2),`
find `intsin^4x\ dx`.
Example 2
We are given that if
`I_n=inttan^nx\ dx`,
then `I_n=1/(n-1)tan^(n-1)x-I_(n-2).`
Find `inttan^3x\ dx`.
See the Scientific Notebook version of the same Examples.
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