# Thread: Substituting numbers for variables

1. ## Substituting numbers for variables

Say I want to test x=-2 in the equation -3x^2+3. When I replace x with -2, do I put parenthesis around it? My calculator gives me two different answers for (-2)^2 and -2^2.

2. ## Re: Substituting numbers for variables

Originally Posted by shane805
Say I want to test x=-2 in the equation -3x^2+3. When I replace x with -2, do I put parenthesis around it? My calculator gives me two different answers for (-2)^2 and -2^2.
$(-2)^2$ means the square of negative two: $(-2)(-2)=4$.

$-2^2$ means the negative of two squared: $-(2)(2)=-4$.

3. ## Re: Substituting numbers for variables

Yeah I totally understand that the two are different, just wondering which one to use when solving for x. Say I have -3x^2+3, and I'm solving for x=-2, do I end up with -3(-2)^2 or -3*-2^2? something tells me it's the first of the two..

4. ## Re: Substituting numbers for variables

Originally Posted by shane805
Yeah I totally understand that the two are different, just wondering which one to use when solving for x. Say I have -3x^2+3, and I'm solving for x=-2, do I end up with -3(-2)^2 or -3*-2^2? something tells me it's the first of the two..
That is correct.