Discrete Mathematics Question!?

Hi well I am doing discrete mathematics and I am having trouble with two questions. The First is : Use a proof case to show that min(a, min(b,c)) = min(min(a, b), c) whenever a, b, and c are real numbers. The second one is: Show that the product of two of the numbers 65^1000 - 8^2001 + 3^177, 79^1212 - 9^2399 + 2^2001, and 24^4493 - 5^8192 + 7^1777 is non-negative. Is your proof constructive or nonconstructive? [Hint: Do not try to evaluate these numbers!]