# Math Help - rational expressions

1. ## rational expressions

f(x) =square root of x - 1/x + 2
Determine values of x for which
1) f(x)= 0
2) f(x) will be a real number.

2. ## Re: rational expressions

Originally Posted by Bonganitedd
f(x) =square root of x - 1/x + 2
Determine values of x for which
1) f(x)= 0
2) f(x) will be a real number.
You must learn to post readable questions.

Is it it $\sqrt{\frac{x-1}{x+2}}\text{ or }\frac{\sqrt{x-1}}{x+2}$ or something else altogether?

Learn to use grouping symbols.

3. ## Re: rational expressions

The first one.

4. ## Re: rational expressions

Originally Posted by Bonganitedd
The first one.
In that case you should have posted "f(x) =square root{(x - 1)/(x + 2)}"
See the grouping?

Solve $\frac{x-1}{x+2}\ge 0$.

5. ## Re: rational expressions

X>=1 nt sure abt the denomenator

6. ## Re: rational expressions

Do you know "if a> b and c is positive then ac> bc. If a> b and c is negative then ac< bc."

If x+ 2 is positive, then multiplying both sides by it gives $x- 1\ge 0$. When is x+ 2 positive?

If x+2 is negative, then multiplying both sides by it gives $x- 1\le 0$. When is x+ 2 negative?

8. ## Re: rational expressions

Thanks you all who contributed.
I now understand the problem
1) The expression will be equal to zero if we set the radicand numerator = 0
2)f(x) will be real 1) x is nt = -2
X>=1 or x< -2

9. ## Re: rational expressions

Do you now understand that this was NOT a "rational expression"?