THIS USER ASKED ๐
What is the 25th term of the arithmetic sequence where a1=8 and a9=48 ? answers to choose from. a)113. b)118. c)123. d)128
THIS IS THE BEST ANSWER ๐
First we need to find an “d” that is different from any 2 consecutive members of the sequence. Because the sequence is arithmetic means that the difference between any 2 consecutive members is equal and constant.
This is the formula for any member of the sequence standing “n”
An = A1 + (n-1) * d
d = (a9 – a1) / (9-1)
d = 5
Now we calculate the 25th member:
a25 = a1 + (25-1) * 5
a25 = 128
The answer is d)
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