SOLUTION
Given the question in the image, the following are the solution steps to answer the question.
STEP 1: Write the given equation
STEP 2: Define how to determine if it is a function
Use the vertical line test to determine whether or not a graph represents a function. If a vertical line is moved across the graph and, at any time, touches the graph at only one point, then the graph is a function. If the vertical line touches the graph at more than one point, then the graph is not a function.
STEP 3: plot the graph and perform a vertical line test
Since the vertical lines touch the graph at only one point and following the description given in step 2. This shows that "The equation is a function"