SOLUTION: Evaluate the limit, if it exists: 16-x^2/x^3-64 (x approaches 4) . The answer is suppose to be 0, but i can't seem to get that answer!

Algebra ->  Complex Numbers Imaginary Numbers Solvers and Lesson -> SOLUTION: Evaluate the limit, if it exists: 16-x^2/x^3-64 (x approaches 4) . The answer is suppose to be 0, but i can't seem to get that answer!      Log On


   



Question 179227: Evaluate the limit, if it exists:
16-x^2/x^3-64
(x approaches 4)
.
The answer is suppose to be 0, but i can't seem to get that answer!

Answer by solver91311(24713) About Me  (Show Source):
You can put this solution on YOUR website!

What you have is an indeterminate form. The limit as x approaches 4 is zero for both the numerator and denominator functions. You need to use L'Hôpital's Rule which says (in part) if the limit of the numerator is zero and the limit of the denominator is zero, both as x approaches c, then the limit of the quotient as x approaches c is equal to the limit, as x approches c of the quotient of the first derivitives of the numerator and denominator functions, given that those derivitives exist.

So, take the first derivitive of , , and the first derivitive of , . Now take the limit of the quotient as x approaches 4:



However, the answer is NOT zero. It is .



John