Describe the graph of the equation y = 4. Is the equation a function?

Question:

Horizontal and Vertical Lines:

If we are given the equation of y equal to a number, our graph will be a horizontal line. Is this equation a function? The answer would be yes since it passes the vertical line test. The vertical line test tells us if we draw a vertical line through any point of the graph and it goes through only one point at each line, then it is a function. If it passes through more than one point, it does not. The slope of a horizontal line is zero.

If we are given the equation of x equal to a number, our graph will be a vertical line. Is this equation a function? The answer would be no since it does not pass the vertical line test that we discussed in the previous paragraph. The slope of a vertical line is undefined. We also see that the same x is paired with more than one y which goes against the definition of a function which says each x needs to have only one y value.

Answer and Explanation: 1