Question

Write the first five terms of the geometric sequence in which a1=64 and the common ratio is 5/4

Answer 1

Remember that finding terms in a geometric sequence is done by multiplying the previous term by a common ratio $r$. For example, we can say:

$a_2 = a_1 r$

$a_3 = a_2 r = (a_1 r)r = a_1 r^2$

We have $a_1 = 64$. To find $a_2$, let's multiply this term by $\frac{5}{4}$:

$a_2 = 64 \cdot \frac{5}{4} = 80$

Now, let's use this to find all of our other terms:

$a_3 = 80 \cdot \frac{5}{4} = 100$

$a_4 = 100 \cdot \frac{5}{4} = 125$

$a_5 = 125 \cdot \frac{5}{4} = \frac{625}{4}$

Thus, our terms are 64, 80, 100, 125, and (625/4).