Question

The function has a y-intercept of (0, 4) and a multiplier of 0.8. 1) Whats the initial value? 2) Is it exponential growth or decay? 3) What is the exponential equation?

Answer 1

1) 4

2) exponential decay

3)
`y = 4(0.8)^x`

Explanation:

1) The initial value or an exponential function is the y-intercept.

Let us consider a standard exponential function of the form y(x) = a•bˣ , if you put in x = 0 (initial value) we get:

y(0) = a•bˣ = a•b⁰ = a•1 = a , so the y-intercept is a , which is called the initial value.

Therefore the y intercept is 4

2) Since the multiplier is greater than 0 and less than one, it is an exponential decay

3) standard exponential function of the form y(x) = a•bˣ, at (0,4),

4 = a(b)⁰

a = 4

b = multiplier = 0.8

Therefore:
`y = 4(0.8)^x`