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muminat
4 years ago
6

15 points please help

Mathematics
2 answers:
scoundrel [369]4 years ago
4 0

Answer:

Sn = a1 (1-r^n)/ (1-r)

Step-by-step explanation:

The formula for the sum of a geometric sequence summations is given by

Sn = a1 (1-r^n)/ (1-r)

  where a1 is the first term, r is the common ratio and n is the term number we are summing up to

Ber [7]4 years ago
3 0

Hello from MrBillDoesMath!

Answer:

The second choice,   a1 (1-r^n)/(1-r)

Discussion:

Let

S= a1 + a1*r + a1*r^2 +......+a1* r^(n-1)                  (*)

be a geometric series with n terms

Multiply both sides by "r":

Sr = a1*r + a1*r^2 +...        + a1*r^(n-1) + a1*r^(n)    (**)            

Subtracting (*) from (**) gives

S-Sr = a1 - a1*r^(n)

       = a1 ( 1 - r^(n))

As S=Sr = S (1-r)

S (1-r) = a1 ( 1 - r^(n))

Divide both sides by (1-r)

S = a1 ( 1 - r^(n)) /(1-r)

Thank you,

MrB

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Okay. I will list all the relatively prime numbers up to 331.
2,3,5,7,11,13,17,19,23,29,31,37,41,43,47,53,59,61,67,71,73,79,83,89,97,101, 103,107,109,113,127,131,137, 139, 149, 151, 157, 163, 167, 173, 179, 181, 191, 193, 197, 199, 211, 223, 227, 229, 233, 239, 241, 251, 257, 263, 269, 271, 277, 281, 283, 293, 307, 311, 313, 317, 331.
Okay, so look at this list and see which match up. 
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For B. 10 and 45. Neither of these are relatively prime. 
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But the answer would be D. because to get a relatively prime pair of numbers you have to have both of them not be divisible by the same number. 102 and 312 can be divided 2, so that's not the answer. 10 and 45 can be divided by 5, so that is incorrect. 3 and 51 can be divided by 3, so that is also incorrect. 35 and 72 cannot be divided by the same numbers. 
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so I don't know but just use the internet

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