Mathematics

Mathematics

Problem

Determine the coefficient of x6x^{6} in the Maclaurin series of (1+x)3ln⁡(1+x)(1+x)^{3}\ln(1+x).
Intuitive explanation

You need to find the x6x^6 coefficient in a product of two functions, each with a known series. Start by writing out the Maclaurin series for (1+x)3(1+x)^3 and ln⁡(1+x)\ln(1+x) separately, then multiply them together—collecting all the ways that terms can combine to give x6x^6. This is a convolution problem: you're looking for every pair of terms whose powers add to 6.

Intuitive explanation

You need to find the x6x^6 coefficient in a product of two functions, each with a known series. Start by writing out the Maclaurin series for (1+x)3(1+x)^3 and ln⁡(1+x)\ln(1+x) separately, then multiply them together—collecting all the ways that terms can combine to give x6x^6. This is a convolution problem: you're looking for every pair of terms whose powers add to 6.

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