Answer
4. - x ^ 2 + 13x - 42 <= 0524211r
5. x ^ 2 - 11x - 42 < 0
16 - x ^ 2 + 9x - 8 <= 0
17. x^ 2 -11x+80<0
18. - x ^ 2 + 3x + 4 <= 0
19. x ^ 2 - 12x + 36 <= 0
20. 2x ^ 2 - 32x + 56 < 0
21. x ^ 2 - 10x - 96 < 0
Step-by-step explanation:
Step-by-step explanation:
6:8=9:12=12:16=15:20
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
