How to draw a quadratic graph - ��˿�� Bitesize

A quadratic equation is drawn as a curve on a set of axes. This type of curve is called a parabola and it is symmetrical.
To draw the graph we need coordinates.
We generate these coordinates by substituting values into the quadratic equation.

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Learn how to draw a graph of a quadratic function

Plotting your graph

A quadratic equation is represented as a curve on a set of axes. In order to draw the curve on a graph we require several pairs of coordinates. These coordinates represent the relationship given in the equation.

Eg y = 4 – x²

The y value is always 4 subtract the square of x.

We can make a table of values to create the coordinates. We use substitution to calculate the values.

We replace the value of x for different numbers and record the resulting y value.

These coordinates can then be plotted on a graph.

Have a go

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Click to see a step-by-step slideshow.
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Step 1 – The x axis goes from –2 to 2. We can use these values to find the values of y for the graph.
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Step 2 – Create a table for the x and y values that you will calculate to plot the graph.
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Step 3 – Find the values for y. Start with x = -2. When x = -2, y = 0. Write this in the table.
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Step 4 – Repeat this process for the remaining values, where x = -1, x = 0, x = 1 and x = 2. You have now found all of the values you need to draw your graph!
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Step 5 – Plot a graph using the values you have found. It should go from – 2 to 2 on the x axis, and from 0 to 4 on the y axis.
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Step 6 – Plot the points from your table on the graph. In this example the coordinates are (-2,0), (-1,3), (0,4), (1,3) and (2,0).
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Step 7 - Join the points with a smooth line. Well done – you have drawn a graph of a quadratic function!

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Discover more about this topic from Bitesize.

Algebra

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Plotting your graph

Have a go

Where next?

More on Straight line graphs

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