# Thread: parabola standard form help

1. ## parabola standard form help

i need help putting these into standard for and finding the vertex, focus and directrix. it would be greatly appreciated if you did it step by step.

1) x-2=y^2-10y

2)x^2+8x-y+20=0

thank you very much.

2. Originally Posted by OnMyWayToBeAMathProffesor
i need help putting these into standard for and finding the vertex, focus and directrix. it would be greatly appreciated if you did it step by step.

1) x-2=y^2-10y

2)x^2+8x-y+20=0

thank you very much.
You're going to have to learn to "Complete the Square".

I'll give you a hint.

y^2-10y = (y^2 - 10y + 25) - 25 = (y-5)^2 - 25

You tell me where that 25 came from.

i know how to complete the square. you divided the middle term by 2 and the squared it. you then also added it on the other side. what is next?

thanxs

4. Originally Posted by OnMyWayToBeAMathProffesor
i need help putting these into standard for and finding the vertex, focus and directrix. it would be greatly appreciated if you did it step by step.

1) x-2=y^2-10y
Originally Posted by TKHunny
You're going to have to learn to "Complete the Square".

I'll give you a hint.

y^2-10y = (y^2 - 10y + 25) - 25 = (y-5)^2 - 25

You tell me where that 25 came from.
Originally Posted by OnMyWayToBeAMathProffesor
i know how to complete the square. you divided the middle term by 2 and the squared it. you then also added it on the other side. what is next?

thanxs
Put it in standard form. Either $x = a(y - h)^2 + k$ or $y = a(x - h)^2 + k$.

-Dan