SOLUTION: I need help with constructing this proof. Can you help me? Use the laws of inference to prove that the conclusion is true. Include statements and reasons in your formal proof.

Algebra ->  Proofs -> SOLUTION: I need help with constructing this proof. Can you help me? Use the laws of inference to prove that the conclusion is true. Include statements and reasons in your formal proof.       Log On


   

Question 182391: I need help with constructing this proof. Can you help me?
Use the laws of inference to prove that the conclusion is true. Include statements and reasons in your formal proof.
24. Given: c-> b
a v ~b
c

Prove: a
Thank you, sincerely
freakertennis@yahoo.com
Answer by solver91311(24713) About Me  (Show Source):
You can put this solution on YOUR website!


You are given that c is true and 'if c then b', hence b is true. But you also know that 'a or 'not b' ' is true. In order for an 'or' statement to be true, at least one of its parts must be true. Since we have proven b is true, 'not b' must be false. Since 'not b' is false, the only way for 'a or 'not b' ' to be true is if a is true. QED.


John