Question

Find the 31st term of the following sequence.

9, 15, 21, ...


186
189
195


is there an easy way to do this

Answer 1

Find the nth term for this sequence using Tn = (a2 - a1)n + 2a1 - a2 where a1 is the first term and a2 is the second term, then substitute n = 31

Answer 2

3+6n

Answer 3

the common difference is found by subtracting the second number from the first: i.e 21-15, 15-9, etc...What do you get as the common difference?

Answer 4

First, can you tell if this is an arithmetic or geometric sequence?

Answer 5

tn=a+(n-1)d
here d=15-9=6
a=9
n=31
plug the values and get the solution

Answer 6

to complicated nvm byby

Answer 7

nvm im back explain again plz

Answer 8

t31=9+(31-1)*6
solve

Answer 9

everyone give me a medal thers like a 10 people in here lol

Answer 10

As what @mathstudent55 was saying, when you look at a sequence of numbers you want to see whether the sequence is geometric \(\large a_n=a_1r^{(n-1)}\), or arithmetic \(\large a_n = a_1 +(n-1)d\), by checking to see whether it has a common difference \(\large a_{n-1} - a_n\) or if has a common ratio, \(\large \frac{a_{n-1}}{a_n}\).

Once found, you can easily deduce what type of formula to apply your understanding of the sequence to.

Answer 11

Arithmetic sequence can be of higher tier so you might want to be specific with your formulas. an = a1 + (n - 1)d is for linear sequence

Answer 12

Elaborate?

Answer 13

You can tell if a sequence is linear by comparing a2 - a1 with a3 - a2 and both of them are not 0

Answer 14

Ok, yes you are correct.

Answer 15

There's quadratic sequence, cubic etc

Answer 16

I don't believe this person is that far into understanding these though.. Maybe im wrong! :P

Answer 17

so its 189 ??????????????????????????????? thts what i got

Answer 18

It's better to clarify early than late

Answer 19

Yes 189

Answer 20

You got it @dirtydan667

Answer 21

yayayyayay

Answer 22

You took it away? :(