Question

Suppose y = 48 + 3(2n - 1) is an explicit representation of an arithmetic sequence for integer values n ≥ 1. Find the xth partial sum of the series, as a quadratic function, where x represents the term number.

Answer 1

Answer: 3x2 + 51x

Step-by-step explanation:

Answer 2

$a_n=48+3(2n-1)$

The formula of the sum of the arithmetic sequence:
$S_n=\dfrac{a_1+a__n}{2}\cdot n$
calculate:
$a_1=48+3(2\cdot1-1)=48+3=51$
substitute
$S_n=\dfrac{51+48+3(2n-1)}{2}\cdot n=\dfrac{99+6n-3}{2}\cdot n=\dfrac{96+6n}{2}\cdot n=3n^2+48n$
Your answer is:
$\boxed{f(x)=3x^2+48x}$