Eric Nicholas K's answer to Nima's United Kingdom question.

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Eric Nicholas K
Eric Nicholas K's answer
5997 answers (Tutor Details)
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Warning: Quite lengthy.
Eric Nicholas K
Eric Nicholas K
5 years ago
Alternatively, (c+2)3 - c3 = 2k can be force expanded to eliminate the term in c3:

c3 + 6c2 + 12c + 8 - c3 = 2k
6c2 + 12c + 8 = 2k
3c2 + 6c + 4 = k

And it follows from there.