# Thread: Graphing an equation question

1. ## Graphing an equation question

This is a example of graphing a Quadratic Equation in Standard form:
By the way these are functions

here I have: -2(x-3)+8 (x-3) is raised to the second power

The vertex of this equation is (3,8).I cant figure out why it is not -3,8!!

On another equation it has (x+3) +1 with (x+3) being raised to the second power. On this one the vertex is (-3,1).I cant figure why b, while being negative in both equations, gets two different results.

2. Originally Posted by mr.confused
This is a example of graphing a Quadratic Equation in Standard form:
By the way these are functions

here I have: -2(x-3)+8 (x-3) is raised to the second power

The vertex of this equation is (3,8).I cant figure out why it is not -3,8!!

On another equation it has (x+3) +1 with (x+3) being raised to the second power. On this one the vertex is (-3,1).I cant figure why b, while being negative in both equations, gets two different results.
The vertex form for a parabola is $\displaystyle y=a(x-h)^2+k$ where (h, k) is the vertex. Your equation looks like this:

$\displaystyle y=-2(x-^+3)^2+8$

$\displaystyle V(3, 8)$

Notice the that h must equal +3 because there's a negative sign in the vertex form of the equation. Just remember to change the sign. That's all.

In your second example $\displaystyle y=(x+3)^2+1$, you have a positive sign inside parentheses. The only way that can happen is if h is negative.

$\displaystyle y=(x-^-3)^2+1$

$\displaystyle V(-3, 1)$

Bottom line..when you take that coordinate out of parentheses, change its sign.

3. Thanks for the help!! One more question, how do you guys get the graphics and the math symbols?

4. Originally Posted by mr.confused
Thanks for the help!! One more question, how do you guys get the graphics and the math symbols?
It's called Latex (pronounced Lay' tek) and it's a document markup language of which a subset is installed here.

There a tutorial here.