Quadratic equations part two

We can make a plot of a quadratic equation by plotting y = ax^2 + bx + c

For example let’s work out the value of y for values of x from -3 to 3 in a quadratic equation.

Let’s set the values of a, b and c to a = 1, b = 0 and c = 0 so that y = x^2

xy = x^2
-39
-24
-11
00
11
24
39

When we plot all of these points and draw lines between them, we get this graph

We can get a more accurate graph by plotting more points. If we add in plus and minus 0.5 and 0.25 we would have the following points to plot.

xy = x^2
-39
-24
-11
-0.50.25
-0.250.0625
00
0.250.0625
0.50.25
11
24
39

The plot looks more curved now. Less jaggedly.

Using software, we can plot all of the points for a smooth curve

Notice that when x = 0, y = 0.

x = 0 is the solution to x^2 = 0