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1. Demonstrati prin inductie matematica ca ([tex] n^{3} [/tex] +5n ) divizibil cu 6 , (∀) n ∈ N

Răspuns :

[tex] P_{(1)}: 1+5 =6 adev. pp ca P_{(k)} : k^{3} + 5k div cu 6 dem ca : P_{(k+1)} : (k+1)^{3} +5(k+1) = k^{3}+3 k^{2} +3k +1+5k+5 = k^{3}+5k+3k(k+1)+6= M_{6} +3* M_{2} +6 divizibil cu 6![/tex]