# Thread: Which expression is defined for all real numbers?

1. ## Which expression is defined for all real numbers?

Which expression is defined for all real numbers?
Please explain why the choice that you chose is correct.

Choice 1)
x+3/x^2

Choice 2)
4/(x-2)^2

Choice 3)
5/(x+2)^2

Choice 4)
7/x^2+3

2. ## Re: Which expression is defined for all real numbers?

Originally Posted by sontung
Which expression is defined for all real numbers?
Please explain why the choice that you chose is correct.

Choice 1)
x+3/x^2

Choice 2)
4/(x-2)^2

Choice 3)
5/(x+2)^2

Choice 4)
7/x^2+3
Is choice 4) $\dfrac{7}{x^2}+3$ that is what you posted.
Or is it $\dfrac{7}{x^2+3}$

Choice in which the denominator cannot be zero is the correct answer.

3. ## Re: Which expression is defined for all real numbers?

Originally Posted by Plato
Is choice 4) $\dfrac{7}{x^2}+3$ that is what you posted.
Or is it $\dfrac{7}{x^2+3}$