Observe the two functions on the graph. match each function with a type of function. f(x): cubic linear exponential quadratic g(x): cubic linear exponential quadratic

When you get a straight line, the term used to describe it is linear. Linear means line. So f(x) is a line or linear.

The red line is a little harder. You are going to have to do this by elimination.
It' not a cubic. Every cubic crosses the x axis. There are no exceptions to that statement. So every cubic has at least ONE real solution.

It is not a straight line either. f(x) is a straight line. g(x) could be described many ways but straight is not one of them.

It's not quadratic either. I've made a graph for a quadratic equation all quadratics have the same shape. They look like a tea cup with no handle. The graphs I've made are f(x) = x^2 [red] and f(x) = - x^2 [blue]. Your graph looks nothing like either one of these two.

There is only one answer left and that is exponential. g(x) is exponential. I don't know the formula but a reasonable guess would be something y = 0.2^-x. That's because the y intercept is so small. The y intercept is the point where x = 0 and you only have a y value. So here, the y intercept looks to be about (0,0.2) 

If you are interested, the graph is below. It's the second from the left and is green.