Answer:

Explanation:
we know that
The exponential function is of the form

where
a is the initial value or y-intercept
b is the base or factor growth
r is the rate of change
In this problem we have
looking at the graph
Is a exponential growth function (as the value of x increases the value of y increases)
so

The y-intercept is the point (0,4)
so

substitute

From the graph take the point (1,8)
substitute in the exponential function and solve for b

therefore
The exponential function is equal to
