Question

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

\(-9-3+3+9+...+81\)

Answer 1

we have an arithmetic sequence, whose firs term is -9, and the constant is:
d= -3-(-9)=3-(-3)=...

Answer 2

Would it be \[\huge \sum_{n=0}^{\infty}=(-9+6n)\] because the common difference is 6?

Answer 3

Wait, it should 15 not infinity. :D

Answer 4

That's correct.