Question

Find the coefficient of the x4y2

term in the expansion of
(3x - y)
[ ? ]xy?



URGENT! Picture included

Answer 1

Hello

answer 1215

Explanation:

As exponent of y is even sign is positive

Let's make the Pascal's triangle

`\begin{array}cccccccdegree&x^6&x^5y&x^4y^2&x^3y^3&x^2^y^4&xy^5&y^6\\1&1&1\\2&1&2&1\\3&1&3&3&1\\4&1&4&6&4&1\\5&1&5&10&10&5&1\\6&1&6&15&20&15&6&1\\\end{array}\\\\answer\ 3^4* 15=1215`