Answer:
B n-12 turns into 12 which makes 7n-5 become -1 +7- 5 = 1
as 12 x7 = 84 and -5 + 84 = 79 our end sequence.
Explanation:
how to approach answering questions for hw and for exam
step 1 hw find a diagram exam rewrite the diagram
step 2 hw work out each multiple question
step 3 see below how workings should be
SIGMA TELLS US The nth term is = k
SIGMA TELLS US The bottom value is value we start with _vs
SIGMA TELLS US The top value is the term we end with - te
A n-2 turns into 9 which makes 7n-5 become -2+7-5 = 0
B n-12 turns into 12 which makes 7n-5 become -1 +7- 5 = 1 (12 x7=84 and -5+84 = 79)
we can prove by using nth common term 7 x 12 -5 = 79
C n -1 turns into 5 which becomes -1+7 = 6
D n- 1 turns into 5 which becomes -1+7-5 = 1
we see the sequence given is 2, 9, 16 ....79 it is ascending sequence +7
we know the nth term is 7n-5 as we work out first step ( 2 - 7= -5)
we see the term we end with is either 9 12 or 5 and we see the end term given value is 72 so B is our answer.