Question

What is the 15th term in the sequence?
3 , 12 , 48 , 192 , 768, . . .

Answer 1

Do you know the first step to solving this problem?

Answer 2

First you apply the formula, do you know what that is?

Answer 3

an+a1+(n-1)d

Answer 4

this is a geometric sequence

Answer 5

no arithmetic

Answer 6

how do you figure out whether the series is arithmetic or geometric?

Answer 7

this is a geometric sequence with a common ration of 4

Answer 8

@Morameme1
do you know how?

Answer 9

An arithmetic sequence goes from one term to the next by always adding (or subtracting) the same value.

Answer 10

A geometric sequence goes from one term to the next by always multiplying (or dividing) by the same value.

Answer 11

why? because each term after the first is being multiply by the first number and a fix number?

Answer 12

previous number by a fixed value

Answer 13

You need to multiply by 4.

Answer 14

Until you get to the 12th number, and add.

Answer 15

therefore this will make it a geometric and not arithmetic :D

Answer 16

oh okay

Answer 17

Add them all together.
Like: 3*4= 12; 12*4= 48; 48*4=192 and so on.. When you get to your 12th number, add them all up then you should get - 16777215

Answer 18

Understand?

Answer 19

yea thx

Answer 20

You're welcome.

Answer 21

t1= 3
t2=12
t3= 48
t4= 192

observe
t2/t1= t3/t2= t4/t3= 4
therefore
common ratio (r) =4
the sequence is in geometic progression

Answer 22

t15 =a*r^14
here a= first term = 3
r= 4
plug in the values and get t15