# Rearranging a polynomial

• May 9th 2010, 03:38 PM
frankspencer
Rearranging a polynomial
Hi,

I'm stuck trying to rearrange a simple equation to make x the subject. Any help would be greatly appreciated....

y = 1211.1x2 - 7476x + 9139.7

Cheers...
• May 9th 2010, 03:52 PM
skeeter
Quote:

Originally Posted by frankspencer
Hi,

I'm stuck trying to rearrange a simple equation to make x the subject. Any help would be greatly appreciated....

y = 1211.1x2 - 7476x + 9139.7

Cheers...

if $y = ax^2 + bx + c$ , then ...

$x = \frac{-b \pm \sqrt{b^2-4ac}}{2a}$
• May 9th 2010, 05:30 PM
frankspencer
No y?
But where did the y go?
• May 9th 2010, 05:32 PM
pickslides
Quote:

Originally Posted by frankspencer
But where did the y go?

Skeeter's answer was for when $y= 0$

Another way would be to complete the square. Will be very messy.