Math Is Fun Forum

CoCoOster

Member

Registered: 2006-01-29

Posts: 11

Graphing Quadratic Functions

Please help me. I am in dire need of assistance. I don't know how to change fractions such as 1/7 in a quadratic function. The problem is like this:
y= (-7x^2)+2x
The directions are as follows:
Complete these steps for a function.
a)Tell whether the graph of a function opens up or down.
b)Find the coordinates of the vertex.
c)Write an equation of the axis of symmetry.
For my equation of the axis of symmetry, I got:
-2/2(7)=-2/-14=-1/-7=1/7
Please explain the next step.
Do I round the decimal?
Do I leave 1/7 as a fraction?
HELP!!!!!!!!!!!!!

CoCoOster

Member

Registered: 2006-01-29

Posts: 11

Re: Graphing Quadratic Functions

Please help me. I'm desperate.

Ricky

Moderator

Registered: 2005-12-04

Posts: 3,791

Re: Graphing Quadratic Functions

Is it (-7)(x^2) or (-7x)^2?

---

"In the real world, this would be a problem.  But in mathematics, we can just define a place where this problem doesn't exist.  So we'll go ahead and do that now..."

kempos

Member

Registered: 2006-01-07

Posts: 77

Re: Graphing Quadratic Functions

if it's -7x^2 the function has a maximum (coordinates: (1/7; 1/7)
if its (-7x)^2 it wil have minimum
x= 1/7

you just leave it like this. i don't think you have to change it into decimal.

CoCoOster

Member

Registered: 2006-01-29

Posts: 11

Re: Graphing Quadratic Functions

thanks guys