Question

What is the 15th term of the sequence 5 -10 20 -40 80

Answer 1

How do you obtain the next term (by doing what to the previous term), what do you think ?

Answer 2

n*-2 as

Answer 3

yes, you multiply times -2 to get the next term. So this is therefore a GEOMETRIC sequence.

\(\large\color{black}{ t_n=t_1 \times r ^{n-1} }\)

Answer 4

for any nth term