The Graphs of Quadratic Equations Saturday, 03 August 2019 The Graphs of Quadratic Equations A quadratic equation is an equation that has a x2 value. All of these are quadratics: y = x2 y = x2 + 2 y = x2 + x – 4 y = x2 + 2x – 3 So quadratic means that there must be a x2 in what ever y equals

If you were asked to draw the graph of y = x2 + 2, follow these steps 1) Draw a chart putting in the x values from –4 to +4 x -4 -3 -2 -1 1 2 3 4 The exam writer will probably do this for you

If you were asked to draw the graph of y = x2 + 2, follow these steps 2) Calculate x2 and put these values into the table. Notice that all of these are positive x -4 -3 -2 -1 1 2 3 4 x2 16 9 The values are always positive because a minus time a minus is a plus -3 X –3 = 9 etc.

If you were asked to draw the graph of y = x2 + 2, follow these steps 3) Add the 2 onto the x2 and put these values into the table. x -4 -3 -2 -1 1 2 3 4 x2 16 9 x2 + 2 18 11 6

All you need to do now is to plot the x number against the y number. If you were asked to draw the graph of y = x2 + 2, follow these steps 4) You have done all that the equation asks so you will have the y value. x -4 -3 -2 -1 1 2 3 4 x2 16 9 x2 + 2 18 11 6 y All you need to do now is to plot the x number against the y number.

x -4 -3 -2 -1 1 2 3 4 x2 16 9 x2 + 2 18 11 6 y

The exam writer will probably do this for you If you were asked to draw the graph of y = x2 + x – 4, follow these steps 1) Draw a chart putting in the x values from –4 to +4 x -4 -3 -2 -1 1 2 3 4 The exam writer will probably do this for you

If you were asked to draw the graph of y = x2 +x – 4, follow these steps 2) Calculate x2 and put these values into the table. Notice that all of these are positive x -4 -3 -2 -1 1 2 3 4 x2 16 9 The values are always positive because a minus time a minus is a plus -3 X –3 = 9 etc.

If you were asked to draw the graph of y = x2 + x – 4, follow these steps 3) Add the x onto the x2 and put these values into the table. x -4 -3 -2 -1 1 2 3 4 x2 16 9 x2 +x 12 6 20

If you were asked to draw the graph of y = x2 + x – 4, follow these steps 3) Subtract 4 from these values to obtain x2 + x – 4. x -4 -3 -2 -1 1 2 3 4 x2 16 9 x2 +x 12 6 20 x2 + x – 4 8

All you need to do now is to plot the x number against the y number If you were asked to draw the graph of y = x2 + x – 4, follow these steps 3)You have done all the equation asks so you must have the y value. x -4 -3 -2 -1 1 2 3 4 x2 16 9 x2 +x 12 6 20 x2 + x – 4 8 y All you need to do now is to plot the x number against the y number

x -4 -3 -2 -1 1 2 3 4 x2 16 9 x2 +x 12 6 20 x2 + x – 4 8 y