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Replies: 5   Last Post: Oct 21, 2012 11:06 AM

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 justlooking for someone else Posts: 77 Registered: 12/10/04
Posted: Oct 17, 2012 9:14 PM

Hi,

I have a little problem that I have not been able to get to the form
required. I may need some help.

here is the problem:

if p(x) = ax^2+bx+c is a second degree polynomial, then prove

p(x) = a(x+b/2a)^2 - ((b^2 - 4ac)/2a)

Here I know the roots of the equation for the quadratic equation is
x=(-b+sqrt(b^2-4ac))/2a and the negative of the radicand and also
x=-b/2a is the vertex

Which root is substituted to get the above form. Or in other words,
how do I determine whether I use the negative or the positive radicand
in the above equation to get the form shown above. I have simplified
it all known ways but cannot seem to get it to that form. Am I
barking up the wrong tree here?

thanks

s