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The first four terms of a geometric sequence are 27, x, 3, 1. find the value of x

User Porsche
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Final answer:

The value of x in the geometric sequence 27, x, 3, 1 is found by equating the ratios between the consecutive terms, solving the resulting equation x^2 = 81, and determining that x = 9 since the sequence is decreasing.

Step-by-step explanation:

To find the value of x in the geometric sequence 27, x, 3, 1, we can use the property that the ratio between consecutive terms is constant. Given that the second term is x and the third term is 3, we can write:

r = x / 27 (ratio from the first to the second term)

r = 3 / x (ratio from the second to the third term)

By equating the two expressions for r, we get:

x / 27 = 3 / x

Cross multiply to get:

x2 = 27 * 3

x2 = 81

Thus, we find:

x = √81

x = 9 or x = -9

However, since x must form a decreasing sequence from 27 down to 1, the negative value does not fit the context. Therefore, the value of x is 9.

User RP Niemeyer
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