How to Graph Quadratics
- 1). Make a table of x and y values.
- 2). Plug in the number zero. If the function is y = x^2 + 3x + 2, for instance, the function will equal 2.
- 3). Plug in some positive numbers. x = 1 makes y equal 6, x = 2 makes y equal 12, and x = 3 makes y equal 20.
- 4). Plug in some negative numbers. x=-1 makes y equal 0, and x=-2 also makes y equal 0. This suggests that the lowest point on the graph must occur when x is halfway between -1 and -2. When x=-1.5, y equals -0.25.
- 5). Plug in more negative numbers that are less than -1.5. Try plugging in -3, -4, and -5.
- 6). Plot the points in your table, on a set of x and y axes. Make sure that the data, graphed, produce a parabola-shaped curve, symmetrical about its vertex.
Source...