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2x^2 - 15x - 3 = 0 I used to remember how to do this in

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Futuristic
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2x^2 - 15x - 3 = 0 I used to remember how to do this in [#permalink] New post   26 Jun 2006, 23:53
2x^2 - 15x - 3 = 0

I used to remember how to do this in school, but have forgotten recently. A related question is: can I expect to see a question like this on the GMAT, where the roots are not simple?



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Re: 2x^2 - 15x - 3 = 0 I used to remember how to do this in [#permalink] New post   27 Jun 2006, 02:36
To solve quadratic equation such as

ax^2 + bx + c = 0

1) Find the product of Coeff. of x^2 and the constant term => a * c
2) Factor it and find factor whose sum or difference equals to coeff of x => means it equals b
3) Split the x part with those factors and solve the equation.


And yes you can get this type of problem in GMAT
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Re: 2x^2 - 15x - 3 = 0 I used to remember how to do this in [#permalink] New post   27 Jun 2006, 11:24
humans wrote:
To solve quadratic equation such as

ax^2 + bx + c = 0

1) Find the product of Coeff. of x^2 and the constant term => a * c
2) Factor it and find factor whose sum or difference equals to coeff of x => means it equals b
3) Split the x part with those factors and solve the equation.


And yes you can get this type of problem in GMAT


I don't think you got my point. This equation has no simple roots. Try finding a way to split 15 so that you can factor the equation, and you'll see what I'm getting at...
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Re: 2x^2 - 15x - 3 = 0 I used to remember how to do this in [#permalink] New post   27 Jun 2006, 14:42
Roots of an equation

ax^2+bx+c are

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

I think you may encounter these questions but not with imagimary roots ( i.e when b^2-4ac is -ve
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Re: 2x^2 - 15x - 3 = 0 I used to remember how to do this in [#permalink] New post   28 Jun 2006, 09:05
plz have a look to the following link [url][u]https://home.earthlink.net/~djbach/precalc.html#anchor1639263
It is well explained in case u need more help PM ME
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Re: 2x^2 - 15x - 3 = 0 I used to remember how to do this in [#permalink] New post   28 Jun 2006, 10:32
Thanks! This information is precicely what I was looking for.



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Re: 2x^2 - 15x - 3 = 0 I used to remember how to do this in [#permalink]
28 Jun 2006, 10:32
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