Question

Which best describes the relationship between the successive terms in the sequence shown? 9, –1, –11, –21, … The common difference is –10.  The common difference is 10.  The common ratio is –9. The common ratio is 9.

Answer 1

Note that subtracting 10 from 9 results in -1, subtracting 10 from -1 results in -11, and so on.  So the common difference is -10.

Answer 2

The difference is -10 because

9-10= 1
-1-10= -11
-11-10= -21

common difference means you add and common ratios means you multiply.

hope this helps!