# Thread: help me in this limit

1. ## help me in this limit

limitation of square root (x^2+3x+4/x^3+1) as x approaches -1.

i don't know how to get the rationalize of 1/square root of (X^3 +1)

thanks

2. Originally Posted by cutiemike1
limitation of square root (x^2+3x+4/x^3+1) as x approaches -1.

i don't know how to get the rationalize of 1/square root of (X^3 +1)

thanks
If you mean $\sqrt{\frac{x^2+3x+4}{x^3+1}$, then the limit is equal to +oo since the denominator --> 0+ and the numerator is positive. Further, if this is what you meant, then it should be written as the limit as x --> -1 from the right.

If you didn't mean that, then I suggest you post in a much less ambiguous format and, perhaps, re-check the question.

3. Originally Posted by mr fantastic
If you mean $\sqrt{\frac{x^2+3x+4}{x^3+1}$, then the limit is equal to +oo since the denominator --> 0+ and the numerator is positive. Further, if this is what you meant, then it should be written as the limit as x --> -1 from the right.

If you didn't mean that, then I suggest you post in a much less ambiguous format and, perhaps, re-check the question.
\sqrt{\frac{x^2+3x+4}{x^3+1}

yup! you're right, that is what i meant..
i tried doing this, separating the square root of both numerator and denominator, then apply rationalize, and my problem is i don't know how to get the rational of \frac{1}{\sqrt{x^3+1}}....

4. Originally Posted by cutiemike1
\sqrt{\frac{x^2+3x+4}{x^3+1}

yup! you're right, that is what i meant..
i tried doing this, separating the square root of both numerator and denominator, then apply rationalize, and my problem is i don't know how to get the rational of \frac{1}{\sqrt{x^3+1}}....
Why do that? My earlier post shows you the way.