Question

Which figure correctly demonstrates using a straight line to determine that the graphed equation is not a function of x?
On a coordinate plane, a circle is centered around (0, 0). A vertical line touches the edge of the circle at (negative 4, 0).
On a coordinate plane, a circle is centered around (0, 0). A horizontal line touches the edge of the circle at (0, 4).
On a coordinate plane, a circle is centered around (0, 0). A vertical line goes through 2 points of the circle
On a coordinate plane, a circle is centered around (0, 0). A horizontal line goes through 2 points of the circle

Answer 1

major hint: to determine if a graph is a function or not, we apply the vertical line test: if there exists a vertical line that crosses the function more than once, it's not a function. so you should be looking for a graph where a vertical line crosses the graph multiple times.