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Deon588

Member

Registered: 2011-05-02

Posts: 68

Finding the equation of 2 different parabolas

Hi. all: I have no idea how to find the equations of these parabolas
(c) It passes through the points (0;0), (1;2) and ( 2; 22).
(d) The x–intercepts are 4 and 2 and the maximum y–value is 6. (Hint:
the axis of symmetry lies half–way between the two x–intercepts.) I know I have to use the formula a(x-r1)(x-r2)=6 How do i find A?  As for (c) I have no idea .  Thanks in advance
Deon

Bob

Administrator

Registered: 2010-06-20

Posts: 10,621

Re: Finding the equation of 2 different parabolas

hi Deon588

(c)  Assume the equation has the form

Substitute the coordinates to get

That should enable you to get a, b, and c.

(d)  You are right about the form here

Use the hint.  Halfway is x = 3 so

You can get 'a' from this.

Post again if you need more detail

Bob

Last edited by Bob (2011-05-26 19:58:11)

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Children are not defined by school ...........The Fonz
You cannot teach a man anything;  you can only help him find it within himself..........Galileo Galilei
Sometimes I deliberately make mistakes, just to test you!  …………….Bob

Deon588

Member

Registered: 2011-05-02

Posts: 68

Re: Finding the equation of 2 different parabolas

Hi Bob.  Thanks a lot it works out perfect now.

Bob

Administrator

Registered: 2010-06-20

Posts: 10,621

Re: Finding the equation of 2 different parabolas

You're welcome. 

Bob

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Children are not defined by school ...........The Fonz
You cannot teach a man anything;  you can only help him find it within himself..........Galileo Galilei
Sometimes I deliberately make mistakes, just to test you!  …………….Bob