GeminiHeat wrote:
In a geometric sequence, each term is a constant multiple of the preceding one. If the third and fourth numbers in the series are 8 and -16, respectively, what is the first term in the sequence?
(A) -32
(B) -4
(C) 2
(D) 4
(E) 64
In a geometric sequence, each term is a constant multiple of the preceding one. If the third and fourth numbers in the series are 8 and -16, respectively...So, if k = the constant multiple, we can write: term4 = (k)(term3)
We get: -16 = (k)(8), which means k =
-2.....what is the first term in the sequence?Now that we know the value of k, we can find other terms.
For example, we know that term3 = (
-2)(term2), which means: 8 = (
-2)(term2), which means term2 = -4
Likewise, since term2 = (
-2)(term1), we can write: -4 = (
-2)(term1), which means term1 = 2
Answer: C
Cheers,
Brent