
Quadratic formula
I need help getting the variable b by itself
http://www.purplemath.com/modules/quads/qform01.gif
this is what i have so far but need help finishing it. If you could show step by step instructions that'd be great.
(2a)http://www.purplemath.com/modules/quads/qform01.gif(2a)
2ax=b +/ sqrt(b^24ac)
+b +b
(2ax+b)^2= +/sqrt( b^24ac)^2
(2ax+b)^2= b^24ac

Re: Quadratic formula
If you are trying to take the quadratic formula and solve for $\displaystyle b$, it will be far simpler to take the quadratic from which the formula is derived, and solve that for $\displaystyle b$:
$\displaystyle ax^2+bx+c=0$
$\displaystyle bx=(ax^2+c)$
$\displaystyle b=\frac{ax^2+c}{x}$

Re: Quadratic formula
I know t would be easier to do it that way but the question asks to go from the formula i posted but thanks!

Re: Quadratic formula
Well, we can begin with the quadratic formula:
$\displaystyle x=\frac{b\pm\sqrt{b^24ac}}{2a}$
$\displaystyle 2ax=b\pm\sqrt{b^24ac}$
$\displaystyle 2ax+b=\pm\sqrt{b^24ac}$
$\displaystyle 4a^2x^2+4abx+b^2=b^24ac$
$\displaystyle 4a^2x^2+4abx+4ac=0$
With $\displaystyle a\ne0$ we have:
$\displaystyle ax^2+bx+c=0$
Now, follow my first post.