What is the sum of a 30-term arithmetic sequence where the first term is 71 and the last term is -103? (3 points)

-480

-448

-416

-384

Question

What is the sum of a 30-term arithmetic sequence where the first term is 71 and the last term is -103? (3 points)
		
-480
		
-448
		
-416
		
-384

jumperman · Answer

I believe it's -416, you can check my work, I might be wrong.

anonymous · Answer

Can u explain please ?

anonymous · Answer

@phi @SolomonZelman @Solver  @mathstudent55

mathstudent55 · Answer

The sum of n terms of an arithmetic series is:

$S_n = \dfrac{n(a_1 + a_n)}2$

where $S_n$ = sum of n terms
$a_1$ is the first term, and 
$a_n$ is the $n$th term

mathstudent55 · Answer

$S_{30} = \dfrac{30[73 + (-103)]}2 $

anonymous · Answer

$$S _{30}=-450$$

anonymous · Answer

Can someone help me finish it please

anonymous · Answer

@ganeshie8

anonymous · Answer

Please help me finish this

ganeshie8 · Answer

first term = 71 , so evaluate below :

$\large S_{30} = \dfrac{30[\color{Red}{71} + (-103)]}2$

anonymous · Answer

-480

anonymous · Answer

Thank You so much @ganeshie8

ganeshie8 · Answer

yw

mathstudent55 · Answer

Sorry, I wrote 73 for the first term by mistake. It was 71.
Answer is -480.