Question

Write an exponential function in the form y=ab^xy=ab^x that goes through points (0, 20) and (3, 1280).

Answer 1

y = 20
`4^(x)`

Explanation:

Use the points to find the values of a and b

Using (0, 20 ) , then

20 = a
`b^(0)` [
`b^(0)` = 1 ] , then

20 = a

y = 20
`b^(x)`

Using (3, 1280 ) , then

1280 = 20 b³ ( divide both sides by 20 )

64 = b³ ( take the cube root of both sides )

`\sqrt[3]{64}` = b , that is

4 = b

Then exponential function is

y = 20.
`4^(x)`