Binomial Theorem · Exercise 48

In the expansion of ${\left(5x+3y\right)}^n,$ each term has the form $\left(\begin{array}{c}n\\ k\end{array}\right)a^{n–k}{b}^k$, where $k$ successively takes on the value $0,1,2,...,n.$ If $\left(\begin{array}{c}n\\ k\end{array}\right)=\left(\begin{array}{c}7\\ 2\end{array}\right),$ what is the corresponding term?

OpenStax, Algebra and Trigonometry 2e · §13.6 Binomial Theorem · Exercise 48