Andrew M. answered • 10/06/18
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Mathematics - Algebra a Specialty / F.I.T. Grad - B.S. w/Honors
Sum up the number of logs.
Multiply the sum by 57
(25+23+21+19+17+15+13+11+9+7+5+3+1)57 = ______ kg
Andrew M.
Yes. Arithemetic series with 13 terms, common difference d -2, a1 = 25
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10/08/18
Andrew M.
starting at a1 = 25, d=-2, n=13
an = a1 + (n-1)d
a13 = 25 + (13-1)(-2) = 25 + 12(-2) = 25 -12 = 1
sn = n(a1 + an)/2
s13 = 13(25+1)/2 = 338/2 = 169
169(57) = 9633 kg
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(25+23+21+...1)(57) = 169
169(57) = 9633 kg
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10/08/18
Jojo J.
why is the common difference is -2? :(
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10/09/18
Jojo J.
why is the common difference is -2?
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10/09/18
Jojo J.
I already know now, :) thank you very much <3
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10/09/18
Jojo J.
10/08/18