How to graph a hyperbola?

Question

So this is the queation of a hyperbola: $$xy=4$$ It's not in it's standard form, how can I graph it this way?

Answer 1

Let us sketch the graph: $$y=\frac{1}{x}$$

How does value change when $x$ changes from positive side to infinity? How does $y$ changes as $x$ changes from $0$ to negative infinity? Graph is something like this:

For positive $x$; as for negative $x$:

http://www.wolframalpha.com/input/?i=y%3D1%2Fx

Check please,

http://www.wolframalpha.com/input/?i=y%3D4%2Fx