## Algebra: A Combined Approach (4th Edition)

$25\pi y^{2}$
We are given that the circle has a radius of $5y$ centimeters. We know that the area of a circle is calculated as $area=\pi r^{2}$. Based on the power of a product rule, we know that $(ab)^{n}=a^{n}b^{n}$ (where $n$ is a positive integer and $a$ and $b$ are real numbers). Therefore, $area=\pi\times(5y)^{2}=\pi\times5^{2}\times y^{2}=25\pi y^{2}$.