Question

the tenth eleventh and twelfth terms of a sequence are shown in the table below:
term number:10|11|12|
term: 21|24|27
which of the following shows the first five terms of sequence?

Answer 1

a.)9,6,3,0,-3
b.)-6,-3,0,3,6
c.)6,3,0,-3,-5
d.)-9,-6,-3,0,3

Answer 2

Can you read this and do it? http://www.mathsisfun.com/algebra/sequences-sums-arithmetic.html
You will set up at least 2 equations and find a. Then you can find the 2nd to 5th terms. Or you can do this manually and subtract the common difference backwards.

Answer 3

well look at the 10th term, the sequence is arithmetic with a common difference d = 3

the formula for a term in an arithmetic sequence is

\[a_{n} =a +(n - 1)d\]

a = 1st term, n = number of terms and d = common difference.

so you can say

\[21 = a +(10 - 1) \times 3\]

solve for a, the 1st term.

when you know a, the 1st term just add 3 for the 2nd and then add another 3 for the 3rd term

hope it helps

Answer 4

@campbell_st Not sure if this user can see the equation notations but I cannot.

Answer 5

and no need for wolfram alpha

Answer 6

im still confused

Answer 7

Manually, you can do a table starting from 10, 11, 12 like this: http://sketchtoy.com/58445088 and so on. It's a desperate move.

Answer 8

I love how my lines were straight in the beginning. (Free hand btw)

Answer 9

so its b?

Answer 10

Yep looks like it.

Answer 11

ok... so do you think you can solve

21 = a + 27

for a...

that will be the 1st term in the sequence

Answer 12

first term is negative 6

Answer 13

correct... and you are adding 3 to get the next term... then keep adding 3...

that as simple as it is

Answer 14

thanks guys :)

Answer 15

You're welcome. Have a good night.