#1
Ive forgotten how to find the vertex of a quadratic graph :/

the equation is y=-2(x+2)(x-1)

thanx in advance.

how you worked it out would be helpful.
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#2
I think the variables are h,k other than that i dunno sorry
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#3
i'm a bit rusty, but i think you differentiate it and then find when its equil to 0
there might also be a way by completeing the square, but i can't remember it in enough detail to be any help
#4
The vertex is, I believe, -b/2a. So if you factor that equation out, you've got. -2x^2-2x+4. So, b is -2, and a is also -2. -b/2a + -(-2)/2(-2)

2/-4 = -1/2

Now plug that in as your y variable, and figure out the x. Then you'll have the two coordinates of the vertex.

EDIT: Did anyone actually read TS's post? Or did you all just look at the title?
#5
Look up the vertex formula.

I'm pretty sure they have one.
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#6
Quote by cokeisbetter
The vertex is, I believe, -b/2a. So if you factor that equation out, you've got. -2x^2-2x+4. So, b is -2, and a is also -2. -b/2a + -(-2)/2(-2)

2/-4 = -1/2

Now plug that in as your y variable, and figure out the x. Then you'll have the two coordinates of the vertex.

EDIT: Did anyone actually read TS's post? Or did you all just look at the title?



That equation sounds awfully familiar, I guess I didn't realize it was for the vertex of a quadratic or I might've been able to help
They credited us with the birth of that sort of heavy metal thing. Well, if that's the case, there should be an immediate abortion.


-Ginger Baker
#7
thanx coke...i had already done half of it but using "h" and k(that didnt go so well)...your way seems A LOT easier.
"Like a midget at a urinal, I was going to have to stay on my toes"

"Like a blind man at an orgy, I was going to have to feel my way through"

#8
Quote by YngwieJnr
thanx coke...i had already done half of it but using "h" and k(that didnt go so well)...your way seems A LOT easier.

Luckily for you, it's the only bit of last year's maths that I remember.