Please help, this is my review, and I have a test tomorrow. But based on what I did, none of my answers matched the ones below.

  a)  21, 34.5, 54.75, 85.125

Step-by-step explanation:

All of the answer choices differ in the first term, so that is the only one you need to figure here. However, we will do them all, so you can see it done.

We note that x > 0 for all of the values of x that we need to use. That means the recursive relation is the one we're using for computation.

f(1) = 3/2·f(0) +3 = (3/2)(12) + 3 = 18 +3 = 21 . . . . . . matches choice (a)

f(2) = 3/2·f(1) +3 = (3/2)(21) +3 = 63/2 +3 = 69/2 = 34.5

f(3) = 3/2·f(2) +3 = (3/2)(34.5) +3 = 51.75 +3 = 54.75

f(4) = 3/2·f(3) +3 = (3/2)(54.75) +3 = 82.125 +3 = 85.125

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When you're computing for sequential input values, each depends on the previous value you computed.

Additional comment

Using an exponential regression calculator (or spreadsheet), the explicit function can be found to be ...

  f(x) = 18·1.5^x -6

practice. practice. practice.