Question

What is the sum of the first 703 terms of the sequence -5, -1, 3, 7, ...?

Answer 1

Answer:

983497

step-by-step explanation:

The sum formula of arithmetic sequence is given by:

$S_n = \frac{n}{2}(2a_1 +(n - 1)d$

a_1 is the first term, n is the nth term and d is the common difference

From the given information

$d = - 1 -( - 5) = - 1 + 5 = 4$

$a_1 = - 5 \: and \: n = 703$

By substitution we obtain:

$S_{703}= \frac{703}{2}(2( - 5) +(703- 1)4)$

$S_{703}= \frac{703}{2}( - 10 + 2808)$

$S_{703}= \frac{703}{2}(2798)$

$S_{703}=98397$

Answer 2

Answer:

S = 983,497

Step-by-step explanation:

We are given the following sequence and we are to find the sum of the first 703 terms of this sequence:

$-5, -1, 3, 7, ...$

Finding the common difference $d$ = $-1-(-5)$ = $4$

$a_1=-5$

$a_n=?$

$a_n=a_1+(n-1)d$

$a_n = - 5 + ( 7 0 3 - 1 ) 4$

$a _ n = 2803$

Finding the sum using the formula $S_n = \frac{n}{2}(a_1+a_n)$.

$S_n = \frac{703}{2}(-5+2803)$

S = 983,497