<h3>
Two possible answers: 6 or -6</h3>
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Explanation:
r = common ratio
To get any term in a geometric sequence, we multiply the previous term by r.
So that means 4r is the second term, since 4 is the first term.
The third term is (4r)*r = 4r^2, which is equal to 9 as given to us.
4r^2 = 9
4r^2 - 9 = 0
(2r)^2 - (3)^2 = 0
(2r - 3)(2r + 3) = 0 ... difference of squares rule
2r-3 = 0 or 2r+3 = 0
2r = 3 or 2r = -3
r = 3/2 or r = -3/2
r = 1.5 or r = -1.5
We can use each r value to find the possible second term
S = 4r = 4*(1.5) = 6
S = 4r = 4*(-1.5) = -6
The second term is either 6 or -6.
We could have this sequence: 4, 6, 9, ...
Or we could have this sequence: 4, -6, 9, ...
