Find K So That The Numbers 2k+1, 3k+4, And 7k+6 Form A Geometric Sequence., A. 2; -1 , B. -2; 1 , C. 2; 1 , D. -2; -1
Find k so that the numbers 2k+1, 3k+4, and 7k+6 form a geometric sequence.
a. 2; -1
b. -2; 1
c. 2; 1
d. -2; -1
Answer:
A. 2, -1
Step-by-step explanation:
Geometric sequences have a common ratio (r) which can be obtained by dividing a term by the one before it.
r =
Get rid of the denominators/cross-multiply.
(3k + 4)² = (7k + 6)(2k + 1)
9k² + 24k + 16 = 14k² + 19k + 6
0 = 14k² - 9k² + 19k - 24k + 6 - 16
0 = 5k² - 5k - 10
0 = k² - k - 2
Factor out.
0 = (k - 2)(k + 1)
k = 2, -1
Hope this helps!
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