# Math Help - Multiple of Infinity

1. ## Multiple of Infinity

What would infinity multiplied by minus 1 be?
Not sure if it would be infinity or minus infinity.

Sorry if this is the wrong part of the forum.

2. Originally Posted by drLef
What would infinity multiplied by minus 1 be?
Not sure if it would be infinity or minus infinity.

Sorry if this is the wrong part of the forum.
If you are talking about ordinary operations on numbers, infinity is not a "number" and so "infinity multiplied by negative 1" (not "minus" 1) is not anything- it has no meaning. There are ways of defining systems that include "infinity" and "negative infinity" and in some of those, yes, "infinity multiplied by negative 1" is "negative infinity".

3. Originally Posted by drLef
What would infinity multiplied by minus 1 be?
Not sure if it would be infinity or minus infinity.

Sorry if this is the wrong part of the forum.
You can abuse this meaningless statement to work with limits.
If a function has infinite limit then negative of the function has negative infinite limit.