Which answer is the explicit rule for the sequence 11, 8.5, 6, 3.5, 1 ?

an=13.5+2.5n
an=13+2.5n
an=13.5−2.5n
an=13−1.5n

an=13.5−2.5n

Step-by-step explanation:

To find the common difference

Take the end term and subtract the first term

8.5 -11 = -2.5

Take the third term and subtract the 3rd term to verify

6-8.5 = -2.5  check

The formula for an arithmetic sequence is

an = a1+d(n-1)

an = 11 -2.5(n-1)

Distribute

an = 11 -2.5n+2.5

Combine terms

an = 13.5 - 2.5n

answer: the proof is mentioned below.

step-by-step explanation:

since, given:   lines bc = ef

prove:   lines ac > ef

          statements                                           reason

1. bc=ef                                           1. given

2. ac= ab+bc                                 2. because b is the point between the  

                                                            line segment ac

3.   ac > bc                                       3. because if a line segment is equal to

                                                          the sum of two line segments then it is

                                                          always greater then each of these

                                                          individual line segments

4. ac > ef                                         4. by equality property.