Question

find the missing term of each geometric sequence
3,__, 12

Answer 1

@whpalmer4

Answer 2

There are a number of ways to go about this one. Do you know the formula for the nth term of a geometric sequence?

Answer 3

no well maybe
\[An=a \times r^{n-1}\]

Answer 4

@whpalmer4

Answer 5

Okay, so we have \(a_1 = 3\) and \(a_3 = 12\)
if \(r\) is the common ratio, then
\[a_2 = a1_*r\]\[a_3 = a_2*r = (a_1*r)*r\]

Answer 6

\[a_3 = a_1*r^2\]\[\frac{12}{3} = r^2\]\[r=\]

Answer 7

r=2

Answer 8

right

Answer 9

so will it be An=3 * 2^2-1???? will that be the equation we use to find the 2nd term

Answer 10

@whpalmer4

Answer 11

r = 2. so \[a_n = a_1*r^{n-1} = 3*2^{n-1}\]

Answer 12

if we are trying to find the 2nd term then n=2 right

Answer 13

@whpalmer4

Answer 14

i figured it out thank you

Answer 15

so what is the second term?

Answer 16

6

Answer 17

very good. how about the 10th term? :-)