(2) Distinguish the conclusion of propositional conditions, write the topic in the "known" item and the conclusion in the "verified" item in combination with imprisonment;

(3) In the item of "proof", write all the reasoning processes.

1, synthesis method: generally speaking, using known conditions and some mathematical definitions, axioms, theorems, etc. After a series of reasoning and argumentation, the conclusion to be proved is finally deduced.

2. Analysis method: Generally speaking, from the conclusion to be proved, the sufficient conditions for its establishment are gradually sought, and finally, the conclusion to be proved is reduced to judging an obviously established condition (known conditions, theorems, definitions, axioms, etc.). ).

3. Reduction to absurdity: Generally speaking, assuming that the original proposition is not established, after correct reasoning, the contradiction is finally drawn, which shows that the hypothesis is wrong, thus proving that the original proposition is established.