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.

Step 3

Steps 2 and 3

Step 2

Step 1

Answer 1

Once again, I will quote myself.
"An indirect proof starts off by assuming that the opposite of what you are given is true. Then by having a contradiction in the proof later on, you can say that the original statement is true."
What part doesn't match up?

Answer 2

step 1

Answer 3

Yup.