Which sequences are arithmetic? check all that apply. –8.6, –5.0, –1.4, 2.2, 5.8, … 2, –2.2, 2.42, –2.662, 2.9282, … 5, 1, –3, –7, –11, … –3, 3, 9, 15, 21, … –6.2, –3.1, –1.55, –0.775, –0.3875, …

In an arithmetic sequence, the next term is found by adding a constant term to each number to arrive at the next number. The common difference can be found by subtracting the first term from the second term.

-8.6, -5.0, -1.4, 2.2, 5.8the common difference here is 3.6
-8.6 + 3.6 = -5.0
-5.0 + 3.6 = -1.4
1.4 + 3.6 = 2.2
2.2 + 3.6 = 5.8
so this IS an arithmetic sequence.

2,-2.2, 2.42, -2.662, 2.9282...there is no common difference..so this is not an arithmetic sequence

5,1,-3,-7,-11common difference is -4
5 + (-4) = 1
1 + (-4) = -3
-3 + (-4) = -7
-7 + (-4) = -11
this IS an arithmetic sequence

-3,3,9,15,21...common difference is 6
-3 + 6 = 3
3 + 6 = 9
9 + 6 = 15
15 + 6 = 21
this IS an arithmetic sequence

-6.2, -3.1, -1.55, -0.775, -0.3875...this is not an arithmetic sequence