Answers:
x = -8/5 or x = 8/5
Sum of the first ten terms where all terms are positive = 4092
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Explanation:
r = common ratio
- first term = 4
- second term = (first term)*(common ratio) = 4r
- third term = (second term)*(common ratio) = (4r)*r = 4r^2
The first three terms are: 4, 4r, 4r^2
We're given that the sequence is: 4, 5x, 16
Therefore, we have these two equations
Solve the second equation for r and you should find that r = -2 or r = 2 are the only possible solutions. If r = -2, then 5x = 4r solves to x = -8/5. If r = 2, then 5x = 4r solves to x = 8/5.
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To find the sum of the first n terms, we use this geometric series formula
Sn = a*(1 - r^n)/(1 - r)
We have
- a = 4 = first term
- r = 2, since we want all the terms to be positive
- n = 10 = number of terms to sum up
So,
Sn = a*(1 - r^n)/(1 - r)
S10 = 4*(1 - 2^10)/(1 - 2)
S10 = 4*(1 - 1024)/(-1)
S10 = 4*(-1023)/(-1)
S10 = 4092
95 because if you do the math you’ll get the answer
The key with these problems is to find which function has the closest y-intercept to the graph, and then try to figure out which one best approximates the slope.
Here are our options:
<span>A. y = x + 4
B. y = 4x + 9
C. y = x + 18
D. y = 3x + 22
Which has the closest approximation of the y-intercept?
The y-intercept is not directly given, but we can assume it is less than 10.
That leaves us with A and B.
Which has the closest approximation of the slope?
The graph, on average, seems to move up about 60 and over about 15.
Slope = rise/run = 60/15 = 4. Although the slope isn't exactly 4, it's much closer to 4 than 1, which is slope for option A.
Therefore, the answer is
B) y= 4x + 9
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