Question

Which sequences are arithmetic? Check all that apply.

–5, 5, –5, 5, –5, …


96, 48, 24, 12, 6


18, 5.5, –7, –19.5, –32, …


–1, –3, –9, –27, –81, …


16, 32, 48, 64, 80

Answer 1

C and E

Explanation:

I got it right. 2020

Answer 2

Option C and E are correct.

The sequences which are arithmetic:

18, 5.5, -7, -19.5, -32,....

16, 32, 48, 64, 80

Explanation:

Arithmetic sequence states that a sequence in which a common difference between each consecutive term is constant.

Common difference(d) =
`a_(n+1)-a_n` for every natural number n.

Option A:

-5, 5, -5, 5, -5, .....

5-(-5) = 5+5 = 10 ,

-5 -5 = -10 .....

Since, the common difference for the given sequence is not constant.

Option B:

96, 48, 24, 12, 6

48 -96 = -48

24-48 = -24 ....

Common difference for the given sequence is not constant.

Option C:

18, 5.5, -7, -19.5, -32,....

5.5-18 = -12.5

-7 -5.5 = -12.5 ....

∴Common difference for the sequence is constant.

Option D:

-1, -3, -9, -27, -81 ,....

-3 -(-1) = -3+1 = -2

-9-(-3) = -9+3 = -6 ....

∴Common difference for the sequence is not constant.

Option E:

16, 32, 48, 64, 80

32-16 = 16

48 - 32 = 16 and so on...

∴Common difference for the sequence is constant.

Therefore, the sequences which are arithmetic are:

18, 5.5, -7, -19.5, -32,....

16, 32, 48, 64, 80