Question

What is the value of a fourth term in a geometric sequence for which a1=10 and r=.5

Answer 1

\(\LARGE a_n=a_1\times {\rm r}^{\rm n -1}\)

Answer 2

this is for any geometric sequence.

Answer 3

Now, for the fourth term of any geometric sequence it will read:

\(\LARGE a_4=a_1\times {\rm r}^{\rm 4 -1}\)

\(\LARGE a_4=a_1\times {\rm r}^{3}\)

Answer 4

knowing your a1=10, and r=5, plug that into:
\(\LARGE a_4=a_1\times {\rm r}^{3}\)


and then calculate the \(a_4\).

Answer 5

So the answer would be 1250?

Answer 6

lets see
\(a_4=10\times 5^3\)
\(a_4=10\times 125\)
\(a_4=1250\)

yes, your answer is correct:)

Answer 7

The answer was 1.25...