- #1
Solarfall
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This is supposedly basic but it makes no sense to me. The other topic was very old so I decided to just start a new one.
Given:
If x=0 and y=0 then xy=0.
They say the contrapositive(which they say is always true) is:
If xy!=0 then x!=0 OR y!=0.
But that is exactly false, because NEITHER x can be zero nor can y be zero else xy=0. And that is saying that "x!=0 AND y!=0", this is the only way "xy!=0".
Would someone care to justify this?
EDIT Just changing these strikes because they are very confusing. My original confusing text should still be quoted in the posts below.
Given:
If x=0 and y=0 then xy=0.
They say the contrapositive(which they say is always true) is:
If xy!=0 then x!=0 OR y!=0.
But that is exactly false, because NEITHER x can be zero nor can y be zero else xy=0. And that is saying that "x!=0 AND y!=0", this is the only way "xy!=0".
Would someone care to justify this?
EDIT Just changing these strikes because they are very confusing. My original confusing text should still be quoted in the posts below.
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