vertex of the parabola problem

[ryansmith069]

The vertex of the parabola y = x^2 + 2x - 3 is:

Now can someone tell me how to do this. My mom did it and got (1, -9), I dont know if that is right cuz the work she showed me didn't look too good.

Thanks

 

[Gene]

THE MAGIC FORMULA for y=ax²+bx+c.
The vertex is at
x= -b/2a
Then you plug that x into the original equation to find y of the vertex.

 

[ryansmith069]

Now I am all confuse, thanks for the help by the way. Ok I did it the first time and got (-1,-4) and the second time got (-1,-2). Is either right?

 

[stapel]

Only one (at most) can actually be on the parabola, so plug them into the parabola equation and see which, if either, works.

If you have further questions, please reply showing your work. Thank you.

Eliz.