Proof by Cases 3 Consider the following conjecture: Let m and n be integers. If m is odd then mn+n2 is even. (a) Show that if m is odd and n is even then mn+n2 is even. (b) Show that if m is odd and n is odd then mn+n2 is even. (c) Explain why this shows that the conjecture is true. Proof by contrapositive. Fallacies. 4 Conjecture: If x32x2+1