I understand that infinity is not a number and you can't just multiply it with another number, but for example whilst calculation limit of a function, I come across some number times infinity and I get infinity as a final answer, but what happens when you multiply infinity with a negative number, and again I am only asking for the sake of calculating limit, I have come to point where my limit is $-8*\infty$ and don't really know what to do with it, logically it seems to be $-\infty$, but is it?
[Math] infinity times negative number in Limit calculation
infinitylimits
Best Answer
In a hand-wavy sort of way: yes.
$$\lim_{x \to +\infty} -8x = -\infty.$$
This is read as: "The limit of negative $8x$, as $x$ approaches (positive) infinity, is negative infinity."