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Septic Factorization (Posted on 2015-06-07) Difficulty: 3 of 5
Factorize: (a+b)7 - a7 - b7

Note: For an extra challenge, solve this puzzle without the aid of a computer program or an online calculator.

No Solution Yet Submitted by K Sengupta    
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Solution Solution | Comment 1 of 5
By the binomial expansion:
(a+b)^7 -a^7 -b^7 = a^6b + a^5b^2 + . . .  + ab^6
                             = ab(a^5 + a^4b + . . .  +b^5)
                             = ab(a + b)^5

Not a computer in sight!

  Posted by JayDeeKay on 2015-06-07 15:52:11
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