Amanda did the following proof in her logic class. Which step in the indirect proof did she do incorrectly?

Prove: 9 is divisible by 3.

Step 1: Assume that 9 is divisible by three.
Step 2: 3 times 3 equals nine. 9 divided by three is three.
Step 3: 9 is divisible by 3.

Question

Amanda did the following proof in her logic class.  Which step in the indirect proof did she do incorrectly?
 
Prove:  9 is divisible by 3.
 
Step 1: Assume that 9 is divisible by three.  
Step 2:  3 times 3 equals nine. 9 divided by three is three.
Step 3:  9 is divisible by 3.

parthkohli · Answer

The Step 1 is wrong, we must assume the OPPOSITE of that. Not that same thing.

parthkohli · Answer

Step 1 should have been Assume that 9 is not divisible by 3.

anonymous · Answer

ok, thnx Parth.  And I can't get over your pic xDD.

parthkohli · Answer

Lol I lol at that everytime I see it

anonymous · Answer

yea haha