Posted by **Anamika** on Saturday, December 8, 2012 at 9:50am.

Let a,b,c be positive integers such that a divides b^2 , b divides c^2 and c divides a^2 . Prove that abc divides (a + b + c)7 .

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**Steve**, Saturday, December 8, 2012 at 10:03am
Is that a power?

(a+b+c)^7

?

- urgent -plsee -
**Steve**, Saturday, December 8, 2012 at 10:12am
Haven't worked through all the details, but I think if you consider that the sum of powers of all the terms in the expansion is 7, just examine every combination.

Naturally, all the terms with a^x b^y c^z are divisible by abc.

Consider a^7

a^2 = mc

c^2 = nb

a^7 = a*(a^2)*a^2

= a*(mc)^2*a^2

= a*m^2c^2*a^2

= a*m^2*nb*a^2

= abc*m^2*n*a^2

so, it appears that all of the terms will be divisible by abc.

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**Anamika**, Saturday, December 8, 2012 at 11:06am
Let a,b,c be positive integers such that a divides b^2 , b divides c^2 and c divides a^2 . Prove that abc divides (a + b + c)^7

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