Question

Is the sum the sum of the arithmetic 1635?​

Answer 1

Answer:

1199

Step-by-step explanation:

There are 22 terms in the sum:

23 + 26 + 29 + ... + 80 + 83 + 86 =

= (23 + 86) + (26 + 83) + ... + (53 + 56)

= 109 + 109 + ... + 109

= 11(109)

= 1199

Answer 2

ANSWER

1199

EXPLANATION

The given series is

$\sum_{n=9}^{30}(3n-4)$

To find the first term of this series, we put n=9 into the formula.

$a = 3(9) - 4 = 23$

To find the last term, we put n=30

$l = 3(30) - 4 = 86$

There are 22 terms from the 9th term to the 30th term

The sum of the consecutive n-terms of an arithmetic series is given by;

$S_n= \frac{n}{2} (a + l)$

We substitute n=22, a=23, and l=86 to get;

$S_ {22}= \frac{22}{2} (23 + 86)$

$S_ {22}= 11 \times 109$

$S_ {22}= 1199$