Writing exponential functions | High School Math | Khan Academy

G is an exponential function with an initial value of -2. So, an initial value of -2 and a common ratio of 17th. Write the formula for G of T.

Well, the fact that it's an exponential function, we know that its formula is going to be of the form G of T is equal to our initial value, which we could call a, times our common ratio, which we could call R, to the T power. It's going to have that form. They tell us what the initial value is, it's -2. So this right over here is -2, and we know that the common ratio is 17th. So this is 17th.

So let me just write it again a little bit neater. G of T is going to be equal to our initial value -2 times our common ratio 17th to the T power. Hopefully, this makes sense.

The initial value is this number. Well, if T is equal to zero, then 17 to the zeroth power is 1, and so G of 0, you can view that time as being equal to zero if you view T as time, would be equal to -2. So that would be our initial value.

Then, if you think about every time you increase T by one, you're going to multiply by 17th again. So the ratio between successive terms is going to be 17th. And so that's why we call that the common ratio. Hopefully, you found that interesting.