Graphs. which graphs are functions? Put x into the equation, say 3, so y = 2*3 = 6. So in order for the points to represent a function, for every input into our function, we can only get one value. When a function is given as a graph, we have a nice test we can use to determine if the graph represents a function. Instructional video. We're asked: Do the points on the graph below represent a function? All points must lie along the curve for it to be a function. This test is called the vertical line test. THE VERTICAL LINE TEST A graph (or set of points) in the plane is a FUNCTION if no vertical line contains more than one of its points. At the line which crosses the x axis at 3, y will = 6. Graphs come in all sorts of shapes and sizes. Answer and Explanation: Check out this tutorial and learn how to determine is a graph represents a linear, quadratic, or exponential function! The [math]cos(0) = 1 [/math]and [math]sin(0)=0[/math]. R^2 at SCC In this lesson you will learn how to tell if a line on a graph represents a function by mapping inputs to outputs. So if we look here, they've graphed the point--it looks like negative 1, 3, so that's the point negative 1, 3. Create your free account Teacher Student. If any vertical line intersects the graph more than once, then the graph does not represent a function. We can easily determine whether or not an equation represents a function by performing the vertical line test on its graph. Simple. In algebra, there are 3 basic types of graphs you'll see most often: linear, quadratic, and exponential. For example, consider the function y = 2x + 1. if you know what y equals, say y = 2x. Look at where the graph crosses the X-axis at the point [math]x=0[/math]. If an algebraic equation defines a function, then we can use the notation f (x) = y. If each x value has a unique y value, then the graph represents a function. 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