Math Is Fun Forum

Leeroy2

Guest

Need Help Asap..

Could anyone help me with this problem?

f(x)=-1/2x^2+5x-8

I need to get 5 different things for the answer, the first is the direction that it opens. There were a few other things that were needed, I think
I also really need to know how to convert that into standard form. That is the most important part.

leeroy2

Guest

Re: Need Help Asap..

Bump!
I still need help with this fast. Please someone help me.

JaneFairfax

Member

Registered: 2007-02-23

Posts: 6,868

Re: Need Help Asap..

What five different things do you want to do with the function?

leeroy33

Guest

Re: Need Help Asap..

All i need to know how to do is to convert it into standard form. I think i can do the rest on my own.

careless25

Real Member

Registered: 2008-07-24

Posts: 560

Re: Need Help Asap..

standard form is in the form of highest degree to the lowest degree so the function you provided is already in standard form. goin from x^2 to x^1 to x^0.

leeroy222

Guest

Re: Need Help Asap..

Hmmm, maybe they call it something different then... Idk. the form i need it in, is something like this

2(x - 2)^2 - 6

careless25

Real Member

Registered: 2008-07-24

Posts: 560

Re: Need Help Asap..

It is called the vertex form not standard form.

Vertex form just gives you the vertex of the parabola
to get to vertex form you have to make the equation into a perfect square and then subtract what you added to it.
so get -1/2x^2 + 5x into a perfect square.
f(x)= -1/2x^2 + 5x -8
f(x)=-1/2(x^2-10x)-8
f(x) = -1/2 (x^2-10x+25) - 8 +12.5
f(x) = -1/2(x-5)^2 + 4.5

to make a perfect square from x^2 -10x
you take half of 10 and square it hence 25.
10/2 = 5, 5^2 = 25

to subtract what you added multiply 25 by -1/2 and change sign, so 25*-1/2 = -12.5 and then change sign to get 12.5.

I know my explanation is not clear so ask n i will try and make it clear.

Last edited by careless25 (2009-01-21 17:15:20)