Answer: y = 5(2)^x.
Explanation:
Let's assume that the exponential function is of the form y = ab^x, where a and b are constants to be determined.
Using the point (0, 5):
5 = ab^0
5 = a
Using the point (3, 40):
40 = ab^3
Substitute a = 5 into the second equation:
40 = 5b^3
8 = b^3
b = 2
Therefore, the formula for the exponential function is y = 5(2)^x.