consider the sequence below- what is next term of sequence?

Question

consider the sequence below

 

-8,7,-1,6,5...

 

what is the next term of the sequence

 

 

* i need help as shown in the beginning of the sequence i would think that your multiplying by a negative(because its negative and positive and it continues) but im not sure what the common ratio/common difference is . any help on figuring this out ? also, any tips how to notice a common ratio/common difference easily in an example of a sequence like this on ?

 

thanks.

Answer 1

Common ratio problems will always have the same ratio. If you know it's a common ratio series, you can just divide the first term by the second, and you have your ratio. If we do that, we get -7/8, which is clearly not something we are multiplying by 7 to get -1.

Ditto for a common difference. We are not simply adding 15 here each time.

 

For this sequence, you are actually generating the next term by adding together the 2 preceding terms.  Take note:

 

-8+7=-1

7+-1=6

6+5=11 (this is your next term!)

 

To keep going:

 

5+11=16

11+16=27

and so on