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**teddybear67** Q1)Find, in its simplest form, the coefficient of $\displaystyle x^r$ in the expansion, in ascending powers of $\displaystyle x $ , of $\displaystyle \frac{1}{x-3} $

Q2) Expand $\displaystyle (1+y)^14 $ as a series of ascending powers of $\displaystyle y $ up to and including the term in $\displaystyle y^3$, Simplify the coefficients.

*I got the above part right and derived at the answer of $\displaystyle 1 + 14y + 91y^2 + 364y^3$ *

However, its the following part that i dont get

In The expansion of $\displaystyle (1 + x + kx^2)^14 $, where $\displaystyle k $ is a constant, the coefficient of $\displaystyle x^3$ is zero. By writing $\displaystyle x + kx^2$ as $\displaystyle y $, or otherwise, find the value of k.

Any help is appreciated ^^