find the Lim when X---- -infinity of the following 7X^- cos 4X all divided by X^+15
^ this simbols means to the second power

Is this what you mean?:

\lim_{x\to {\infty}}\frac{7x^{-cos(4x)}}{x^{15}}

Please clarify, do you have to use the Squeeze Theorem on this?

Graph it and see what it looks like. That will help you see the limit.

This is a tricky one. A calculator may even tell you it's undefined. But...

Thanks for your replay, yes the sandwich Thm has to be used to solve this problem, the degree of X in the numerator is 2 and the expression in the denominator is X to the second degree pluss 15. The limit is for X at negative infinity.

The degree of x in the numerator is 2? Then where did the cos4x come from?

the whole expression if a function and the task is to find the limit of tha function.