Graph sketching
When sketching the graph of an unfamiliar function, it might help to think about the following.
- Where does the graph cross the axes?
- When is the function positive and when is it negative?
- Does it have any asymptotes?
- Is it increasing or decreasing?
- What happens as \(x\) gets very large?
- Is it related to any other graphs whose shape I know?
As a check, you could substitute in some values of \(x\) such as \(x=0\), \(1\), \(2\), \(-1\).
If you want a final check of your sketches, you could use a graphical calculator or software such as Desmos. Alternatively, you could use the Interactive graphs section of this resource.
Now sketch the graph of \(y=\dfrac{1}{x^2+a}\) for different values of \(a\).
In addition to the above, you might find it helpful to first sketch the graph of \(y=x^2+a\) (for your chosen value of \(a\)). How does the graph of \(y=\dfrac{1}{f(x)}\) relate to the graph of \(y=f(x)\)?
