Mathematics Stack Exchange is a question and answer site for people studying math at any level and professionals in related fields. Join them; it only takes a minute:

Sign up
Here's how it works:
  1. Anybody can ask a question
  2. Anybody can answer
  3. The best answers are voted up and rise to the top

I need a little help with my homework.

This is the assingment: If: $$ U(x):= \frac{(x+2)^2}{x+1} $$ For what real numbers $x$ is defined: I tried to do that by solving the equation for $x$. I did that in following manner: $$ \frac{(x+2)^2}{x+1} = x+3+\frac{1}{x+1} $$ I got this solution by dividing $(x+2)^2$ with $x+1$. At the end I got that $x$ is $-1$ and $-3$.

Am I on a good track?? Thanks.

share|cite|improve this question
It's defined for every $x\ne -1$ – Riccardo.Alestra Oct 2 '13 at 16:11
Thanks. When I wrote question I figured that out. I fell a little bit stupid right now. – depecheSoul Oct 2 '13 at 16:14
up vote 2 down vote accepted

Your division is correct, but unnecessary.

What we know, however, is that $U(x)$ is defined for all $x\in \mathbb R, \;\;x \neq -1$. When $x = -1$, the denominator of $U(x)$ is zero, and division by zero is undefined.

share|cite|improve this answer
This also needs a TU! +1 – Amzoti Oct 16 '13 at 0:39
A rain of $+$ for you. :-) – Babak S. Oct 21 '13 at 6:59

Your Answer


By posting your answer, you agree to the privacy policy and terms of service.

Not the answer you're looking for? Browse other questions tagged or ask your own question.