# Coding challenge

Write some code that uses the algebra() function to expand $\left(1 + x + x^2 + \cdots + x^{27}\right)\left(1 + x + x^2 + \cdots + x^{14}\right)^2$. What is the coefficient of $x^{28}$? (Ans: 224.) (Ref: ACM 12A 2008.)