Question

Please help thank you very much

Answer 1

You already have the explicit rule for the sequence,

`a_k=3+(k-1)1.5`

Simplify this a bit to get

`a_k=3+1.5k-1.5=1.5+1.5k`

The series that sums these 6 terms is then

`\displaystyle\sum_(k=1)^6a_k=\sum_(k=1)^6(1.5+1.5k)`