Question

which sequences are arithmetic?. –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

–5, 5, –5, 5, –5, … : The differences between terms vary. Not arithmetic.

96, 48, 24, 12, 6 : The differences between terms vary. Not arithmetic.

18, 5.5, –7, –19.5, –32, … : The difference between terms is always -12.5. Arithmetic.

–1, –3, –9, –27, –81, … : The differences between terms vary. Not arithmetic.

16, 32, 48, 64, 80 : The difference between terms is always 16. Arithmetic.

Answer: The third and fifth choices are arithmetic sequences.

Answer 2

16, 32, 48, 64, 80 is an arithmetic sequence.

In an arithmetic sequence, the difference between the consecutive terms is constant. In this case, the difference between each term is 16; this means 16 is added to each term to get the following term.