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Forum URL: http://www.cut-the-knot.org/cgi-bin/dcforum/forumctk.cgi
Forum Name: This and that
Topic ID: 619
Message ID: 0
#0, a + b divides a^3 + b^3
Posted by Koko on Jun-14-05 at 02:06 PM
a and b are integers

I found accidentally that a + b divides a^3 + b^3. I also know why:

a^3 + b^3 = ( a + b )( a^2 - ab + b^2 ).

Then I also found that a - b divides a^3 - b^3 when a <> b, but I am still struggling to find the formula. Could somebody help please.

Thanks