Fran is doing an indirect proof with four given statements and one conclusion. How many of these statements must be false based on her assumption to contradict the assumption and prove the original conclusion?

Exactly three

All four

At least one

None of them

Question

Fran is doing an indirect proof with four given statements and one conclusion.  How many of these statements must be false based on her assumption to contradict the assumption and prove the original conclusion? 

 Exactly three 

 All four 

 At least one 

 None of them

anonymous · Answer

@amistre64
@e.cociuba
@Nurali

anonymous · Answer

Exactly three 

 All four 

 At least one 

 None of them

nurali · Answer

At least one must be false. It is the statement that assumes the theorem being proved is false.

anonymous · Answer

thanks

nurali · Answer

Anytime.