# Is the the sequence #5a-1, 3a-1, a-2, -a-1,...# arithmetic?

##### 1 Answer

**Interpretation 1: Assuming the question is with #a- 2#:**

The common difference,

#d = t_2 - t_1#

#d = 3a - 1 - (5a - 1)#

#d = 3a - 1 - 5a + 1#

#d = -2a#

#d= t_3 - t_2#

#d = a - 2 - (3a - 1)#

#d = -2a - 1#

Since the two numbers aren't the same, this sequence **is not** arithmetic

**Interpretation 2: Assuming the question is with #a - 1#**

Doing the same process as above:

#d = t_2 - t_1#

#d = 3a - 1 - (5a - 1)#

#d = 3a - 1 - 5a + 1#

#d = -2a#

#d = t_3 - t_2#

#d = a - 1 -(3a - 1)#

#d = a - 1 - 3a + 1#

#d = -2a#

Since the two **is** arithmetic.

Hopefully this helps!