Question

A=8 and b=2.25 but what is k

Answer 1

a=8

b=9/4

k = 27

Explanation:

y = ab^x

We know that a is the initial value or when x = 0

We know the point (0,8) so a = 8

y = 8 b^x

Using the point (1,18) for x and y we can find b

18 = 8 * b^1

18/8 = b

9/4 = b

Now

y = 8 * ( 9/4) ^ x

Letting x = 1.5

k = 8 *(9/4)^1.5

k = 27

Answer 2

• a = 8, b = 2.25, k = 27

Explanation:

• y = abˣ

Points on the graph:

• (0, 8), (1, 18), (1.5, k)

Substitute coordinates into equation and solve for and and b:

• 8 = ab⁰ ⇒ 8 = a*1 ⇒ a = 8
• 18 = 8b ⇒ b = 18/8 ⇒ b = 2.25

Find k:

• k = 8*
  `2.25^(1.5)` = 27