Which of the following choices is the common difference between the terms of this arithmetic sequence?

4x + 7y, 8x + 2y, 12x + -3y, 16x - 8y, 20x - 13y, ...

A. 5x + 4y
B. 4x - 5y
C. -5x - 4y
D. 5x - 4y
E. 4x + 5y

Question

Which of the following choices is the common difference between the terms of this arithmetic sequence?

4x + 7y, 8x + 2y, 12x + -3y, 16x - 8y, 20x - 13y, ...

 		A.	5x + 4y
 		B.	4x - 5y
 		C.	-5x - 4y
 		D.	5x - 4y
 		E.	4x + 5y

danjs · Answer

how does each term change for every increase 

4x to 8x  is an increase of +4x

danjs · Answer

7y to 2y  is a decrease of -5y

danjs · Answer

the next terms follow the same process

danjs · Answer

n2 - n1 =

8x + 2y    
4x + 7y    -
---------------
4x -5y

danjs · Answer

= n3-n2  =  n4 - n3 = n5 - n4

anonymous · Answer

would it be C?

danjs · Answer

You subtract the nth term from the (n+1) term ...

8x+2y 
4x+7y  - 
---------- 
4x - 5y <----------common differ

anonymous · Answer

Then it would be B

danjs · Answer

Take any of the terms, then subtract from that the term before it.

danjs · Answer

right