What is the explicit rule for the sequence? 15.5, 13, 10.5, 8, 5.5, 3,  a. an=18−2.5n b. an=15.5−2.5n c. an=18+2.5n d. an=15.5+2.5n (will mark brainliest only if answer is correct)

ANSWER

The explicit rule for the sequence is



EXPLANATION

The terms of the sequence are


The first term of the sequence is

and the constant difference is

Since there is a constant difference, it means the sequence is an arithmetic progression.

The general formula for an arithmetic sequence is given by the formula,



We substitute the above values to obtain,



We expand to obtain,



This will simplify to,



Therefore the correct answer is A.