What is the sum of the arithmetic sequence 152, 138, 124, , if there are 24 terms? (1 points)

-240

-216

-192

-168

Question

What is the sum of the arithmetic sequence 152, 138, 124, , if there are 24 terms? (1 points)
		
-240
		
-216
		
-192
		
-168

hartnn · Answer

could you find the common difference ?

hartnn · Answer

the formula is 
$\Large S_n = (n/2) (2a_1 +(n-1)d)$

a1 = 1st term = 152
n = number of terms = 24
you just need d= common difference = ...

to be able to use this formula

hartnn · Answer

d= common difference = difference between the consecutive terms 
d = 2nd term - 1st term = 3rd term - 2nd term = .... and so on

anonymous · Answer

Ok Let Me Try To Solve It

hartnn · Answer

first find 'd'

anonymous · Answer

(24/2) $$\left( \frac{ 24 }{ 2} \right)\left( 2\times152 \right)+\left( 24-1 \right)d$$

hartnn · Answer

first find 'd' !!
d = 2nd term - 1st term = 3rd term - 2nd term = ....

anonymous · Answer

Im Kind of confused :/

anonymous · Answer

About d

hartnn · Answer

|dw:1402856357907:dw|