What is the explicit formula for this arithmetic sequence?
-12,-17, -22, -27, ...

Step-by-step explanation:

An explicit arithmetic formula in standard form is

where n is the position of a number in thesequence, a1 is the first number in the given sequence, and d is the common difference. The common diff here is -5 since we have to subtract 5 from each term to get to the next one in the sequence. The first number is -12. So

a1 = -12

d = -5 and the explicit formula is

and you could simplify it a bit to

and finally to

which is a linear representation. Arithmetic sequences can all be simplified down to represent lines.

(a) the volume of the cone is 20/3 in3

hence, option a is correct.