# Proving

• Apr 24th 2011, 02:48 PM
mamen
Proving
Our professor asked us to show/prove this: "If A, then B.". We already did everything that we could to answer the given problem; but still we couldn't get the answer.
There really an answer to this??

• Apr 24th 2011, 03:05 PM
Plato
Quote:

Originally Posted by mamen
Our professor asked us to show/prove this: "If A, then B.". We already did everything that we could to answer the given problem; but still we couldn't get the answer.
There really an answer to this??

As written it is a nonsense question.
Did you leave critical information out? What are A & B?
If A is false then "If A then B" is true regardless of what B is.
If B is true then "If A then B" is true regardless of what A is.
The only time then "If A then B" is false is when A is true and B is false.
• Apr 24th 2011, 04:32 PM
mamen
Sir, I guess the statement was this: "Given A, show B." Does it make sense now? thanks sir..
• Apr 24th 2011, 04:45 PM
Plato
Quote:

Originally Posted by mamen
Sir, I guess the statement was this: "Given A, show B." Does it make sense now? thanks sir..

NO
• Apr 24th 2011, 04:50 PM
topsquark
Quote:

Originally Posted by mamen
Sir, I guess the statement was this: "Given A, show B." Does it make sense now? thanks sir..

As Plato has already asked, what are A and B? "Given A, show B" is not always possible. For example when A is "x > 0" and B is "x^2 = -25" you cannot possibly show that, given x > 0 that x^2 = -25. It is impossible.

You need to be much more specific if you expect to have this question answered.

-Dan