Prove that n(n+5) + 2(n+3) is always a product of two numbers with a difference of 5.
n(n+5)+2(n+3) = n2+5n+2n+6 = n2+7n +6 = (n+6)(n+1) = (n+6) x (n+1).
The difference between (n+6) and (n+1) is 5, so this is a product of two numbers with a difference of 5.
EG
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