Question

Which of the following is the general term for the sequence

Answer 1

This is an example of a geometric sequence.  To find for the nth term, we use the formula:

an = a1 r^(n – 1)               ---> 1

Where:

a1= 1st term of the sequence = -a

r = common ratio

To find for the common ratio r, we divide the 2nd term with the 1st term (we can also divide the 3rd term with the 2nd term; we can use any 2 terms as long as they are in succession.)

r = a^2 / -a

r = -a

Substituting a1 and r in equation 1:

an = -a (-a)^(n-1)

Therefore the answer: B) -a(-a)n-1