Question

Find S10 for 1 + 4 + 7 +… and how do I work it out?

Answer 1

this is an arithmatic sequence starting with \[a_0=1\] and a common difference of \[d=3\]
for this, the sum upto n^th term is:
\[S_n={n\over2}[a_0+(n-1)d]\]
plug in the numbers and solve