Question

Write the sum using summation notation, assuming the suggested pattern continues.

-1 + 2 + 5 + 8 + ... + 44

Answer 1

You see that the distance between each term is, 3,
\[5-2=3\]So, you can do the following sum,
\[\sum_{j=1}^{15}(-1+3j)\] That is the answer.

You know that you must sum until j=15 because,
\[44=-1+3j\Rightarrow j=15\]

Answer 2

is this the same as your answer: