SOLUTION: The second term in a geometric sequence is 50. The fourth term in the same sequence is 112.5. What is the common ratio in this sequence?
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Question 978921: The second term in a geometric sequence is 50. The fourth term in the same sequence is 112.5. What is the common ratio in this sequence? Answer by htmentor(1343) (Show Source):
You can put this solution on YOUR website! The nth term of a geometric sequence can be written a_n = a + (n-1)d, where a is the 1st term and d is the common difference
So we can write the 1st 4 terms as
a_1 = a
a_2 = a + d
a_3 = a + 2d
a_4 = a + 3d
Given: a_2 = 50, a_4 = 112.5
subtract a_2 from a_4 to determine d:
a + 3d - (a + d) = 112.5 - 50
2d = 62.5
d = 31.25
