Mark M. answered • 04/02/17
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Mathematics Teacher - NCLB Highly Qualified
An arithmetic sequence has a common difference. Therefore:
(x + 11) - (2x + 1) = (4x + 5) - (x + 11)
Can you solve for x and answer?
Mark M.
The three terms are 9, 15, 21. The common difference is 6.
an = a1+ (n - 1)d
a15 = 9 + (15 - 1)6
Sn = (n/2)(2a1 + (n - 1)d))
S30 = (30/2)(2(9) + (29)(6))
These two formula should have been presented to you!
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04/02/17
Donna O.
thank you. the formulas were given to me. I was confused which of the many formulas to use. I have solved b and c with your help. thank you
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04/02/17
Mark M.
Glad to have helped. You are welcome.
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04/02/17
Donna O.
04/02/17