Thursday, 10 November 2016

integers - Use theory of congruence to prove.....

Use the theory of congruence to prove that 17|(23n+1+3×52n+1) for all integer n1
(23n+1+3×52n+1)=2×8n+15×25n
=17×8n1+374×25n1+25n18n1



=25n18n1
=8n18n1 [since 25\equiv 8\mod 17)
=0\mod 17



0 is divisible by 17




Is this correct?

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