Question

Can someone help me:
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

I think it might be steps 2 and 3, but I'm not sure.

Answer 2

in indirect proof, we start by assuming the OPPOSITE of wat we need to prove as TRUE

Answer 3

Since, we want to prove that " 9 is divisible by 3",
lets assume the opposite is true :- "9 is NOT divisible by 3"

Answer 4

that should be the first step in proof,
2nd step we arrive at a contradiction,
3rd step we conclude

Answer 5

thats the logical flow of any indirect proof. so wat do you think ?

Answer 6

Oh, so step one is incorrect, because she should have assumed it wasn't divisible by 3.

Answer 7

Yup !

Answer 8

Thanks so much ^-^

Answer 9

np :)