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Khalid wrote the sequence below. x - 1, -2x + 2, 4x - 4, -8x + 8. Which formula can be used to find the 10th term of the sequence?
a10 = (x - 1)*(-2)10-1
a10 = (x - 1)10-1
a10 = (x - 1)*(2)10-1
a10 = (x - 1)*(-2)10
Solution:
Given, the sequence is x - 1, -2x + 2, 4x - 4, -8x + 8.
Common ratio, r = (-2x + 2) / (x - 1)
r = -2(x - 1) / (x - 1)
r = -2
Again, r = (4x - 4) / (-2x + 2)
r = 4(x - 1) / -2(x - 1)
r = -2
Therefore, the given series is in geometric progression.
We have to find the 10th term of the sequence.
The n-th term of a geometric sequence is given by an = arn-1
Here, a = x - 1, r = -2, n = 10.
a10 = (x - 1)(-2)10-1
a10 = (x - 1)(-2)9
a10 = (x - 1)(256)
a10 = 256x - 256
Therefore, the 10th term of the sequence is a10 = (x - 1)(-2)10-1 or 256x - 256.
Khalid wrote the sequence below. x - 1, -2x + 2, 4x - 4, -8x + 8. Which formula can be used to find the 10th term of the sequence?
Summary:
Khalid wrote the sequence x - 1, -2x + 2, 4x - 4, -8x + 8. The 10th term of the sequence is a10 = (x - 1)(-2)10-1 or 256x - 256.
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