Choose the main technique to prove the following statement.
If 5 n 2 + 6 n + 7 5 n 2 + 6 n + 7 5n^2+6n+7 is odd, then n n n is even.

Question

Choose the main technique to prove the following statement. 
 If  5 n 2 + 6 n + 7 5 n 2 + 6 n + 7 5n^2+6n+7  is odd, then  n n n  is even.

Answer

T2: indirect proof by contraposition to show  p → q ≡ T p → q ≡ T p 	o q \equiv T

Answer

T1: direct proof to show  p → q ≡ T p → q ≡ T p 	o q \equiv T

Answer

T3: indirect proof by contradiction to show  p ≡ T p ≡ T p \equiv T

Answer

T4: two-step proof to show  p ↔ q ≡ T p ↔ q ≡ T p \leftrightarrow q \equiv T

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