Question

Write the summation that represents the series 15 + 18 + 21 + 24. What is the explicit formula for the series shown?

Answer 1

Answer:

Summation: $\sum_{n=1}^4(3n+12)$

Explicit formula: $a_n=3n+12$

Step-by-step explanation:

The given series is 15 + 18 + 21 + 24.

The first term of this series is $a_1=15$.

The common difference is $d=18-15=3$

The explicit formula is given by: $a_n=a_1+d(n-1)$.

We plug in the known values to get:

$a_n=15+3(n-1)$

$a_n=15+3n-3$

The explicit formula is $a_n=3n+12$

The summation that represents the series is: $\sum_{n=1}^4(3n+12)$