For what value of x is x^2-3x-18?

[AlexB99]

I'm trying to help my brother with his math homework and I'm getting this question wrong. I have no idea what I am doing wrong! I'm currently in linear algebra so sometimes steps for more basic algebra stump me! Please help. We are factoring which gives us (x-6)(x+3) which makes x=0 at 6 and -3. Then we use a line chart where we get:
+++++(-3)----------(6)++++++
However, that is not the answer given.

[StaceyKoprince]

Hello and welcome to the forums! Please make sure to read the forum guidelines before posting. Please post general math questions in the General Math folder; this folder is for overall study strategy questions.

Next, I don't see a full equation. Were you trying to say x^2 – 3x – 18 = 0?

If so, then that equation does factor to (x - 6)(x + 3) = 0. The two solutions are:
x – 6 = 0 --> x = 6
x + 3 = 0 --> x = –3

If, on the other hand, the right-hand side of the equation was not "= 0" then the above is not the solution. For quadratic equations, you first have to set one side equal to 0 before you can factor.