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Math Forum » Discussions » sci.math.* » sci.math.independent

Topic: Please help refresh my Algebra skills (factoring & solving)
Replies: 9   Last Post: Oct 18, 1999 10:23 PM

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dannyboy@here.com

Posts: 682
Registered: 12/6/04
Re: Please help refresh my Algebra skills (factoring & solving)
Posted: Oct 17, 1999 5:50 PM
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On Sun, 17 Oct 1999 15:06:40 -0400, "Nick Marques" <nickjm@jnlk.com>
wrote:

>If I have some nasty numbers in quadratic form, how do I factor and solve
>for the TWO answers??
>
>-4.9x^2+5.5x-105=0
>That factors to x(-4.9x+5.5) = -105

Gets you nowhere. You are looking for two factors of the form
(Ax+B)(Cx+D). The + might be -. However, MUCH easier to use the
quadratic formula, especially in this case as you will see.

Start with positive x^2 (why not?)

4.9x^2 - 5.5x + 105 = 0

Use the formula:

x = (-b +-sqrt(b^2-4ac)/2a to get

x = (5.5 +-sqrt((5.5)^2 - 4*4.9*105))/(2*4.9)

Out with the calculator, and it looks like they might be complex
roots.

Dan.

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