Reciprocal Graphs
In this chapter we shall be looking at reciprocal graphs. You will acknowledge what the reciprocal os a number is and then plotting graphs involving reciprocals.
What is a reciprocal?
The reciprocal of a number is simply one divided by that number.
For example the reciprocal of 4 is;
The reciprocal of 5 is;
The reciprocal of 10 is;
The reciprocal of 2/3 is;
The reciprocal is 2/5 is;
Plotting a reciprocal graph
Suppose we were to plot a graph of 1/x. The following table shows the points we have to plot.
| x | 5 | 4 | 3 | 2 | 1 | 0 | -1 | -2 | -3 | -4 | -5 |
|---|---|---|---|---|---|---|---|---|---|---|---|
| 1/x | 0.2 | 0.25 | 0.33 | 0.5 | 1 | ? | -1 | -0.5 | -0.33 | -0.25 | -0.2 |
If you look carefully you will realise that as x gets very small, 1/x becomes very large. This is why you can’t divide by 0, because as x gets close to zero the answer gets very large it’s impossible to note down.
The following graphs show a reciprocal graph corresponding to the table above.
The following graph examples show graphs involving reciprocals.
Reciprocal graph of y=1/x – 3
Reciprocal graph of y = -1/x
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