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# Algebra 2 Sequences and Series help and confirm if answers are right please.

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1) Find the sum of the arithmetic sequence 7∑  i = 3     (4+i)

Sigma example 1: 7 is above the sigma, i = 3 is below the sigma sign and (4+i) is to the right of the sigma sign.

2) Find the sum of the geometric series 5∑ i = 1      3(2/3)^i

3) Find the sum of the infinite geometric series if it exists 3/2 - 3/4 + 3/8 + 3/16 ......

4) Solve using binomial theorem (2x-3y)^4

Answer: 16x^4 - 96x^3y + 216x^2y^2 - 216xy^2 +81y^4

5) Find the coefficient of x^3 in the expansion of (2x-4)^7

6) Write recursive rule for sequence 7, 20, 33, 46, 59.....

7) Write recursice rule for sequence 27, 36, 48, 64, 256/2.....

Word Problems

1) Containers are stacked in 20 rows with 2 in the top row, 5 in the 2nd row, 8 in the 3rd row, and so on. How many contianers are in the stack?

2) A certain bacteria culture initially contains 5,000 bacteria and increases by 15% every hour, write a rule for the number of bacteria an present after N hours. Then find how many bacteria are present after 12 hours.

3) A diamond mine yealds 1.8 million carats in its first year. Since then the yearly output decresed by 12%. The owner hopes the mine will produce 50 million carats over its lifetime, if the trend continues can the mine produce this many carats in its lifetime? What is the total amount of carats produced by the mine in its lifetime?

Nov 14, 2018
edited by Guest  Nov 14, 2018
edited by Guest  Nov 14, 2018
edited by BLANK  Nov 14, 2018
edited by BLANK  Nov 14, 2018

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$$output = 1.8\times 10^6 \sum \limits_{k=0}^\infty ~(1-0.12)^k = \\ 1.8 \times 10^6 \sum \limits_{k=0}^\infty ~(0.88)^k = \\ 1.8\times 10^6 \dfrac{1}{1-0.88} = \dfrac{1.8\times 10^6}{0.12} = 15 \times 10^6$$

so it won't get anywhere near 50 million carats output.

Nov 14, 2018
#2
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Is the answer to the non word problem 1 56? cuz its 5,6,7,8,9,10,11 and thats 56?

and number 2 is about 5.2?

Nov 14, 2018
edited by BLANK  Nov 14, 2018