Chapter 1 - Section 1.1 - Four Ways to Represent a Function - 1.1 Exercises - Page 18: 10

No

$2xy+5y^2=4$ In this equation, $y$ is not a function of $x$ because for some input values, there are two possible output values. For example, consider $x=1$. We get the following quadratic equation. $5y^2+2y-4=0$ The possible values of $y$ are $\frac{-2\pm\sqrt{84}}{10}$ See image for graph of function. Notice it does not pass the vertical line test.