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September 11th, 2008, 05:55 AM   #1
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Solve Quadratic Equation for x

Hi

I am trying to solve the following equation for x:

8.64 = -0.0033x2 + 0.2496x + 4.2041

I'm not exactly sure how to proceed with this. Would I first subtract 8.64 from both sides so that one side can be set to 0?

Thanks

Peter
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September 11th, 2008, 12:46 PM   #2
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Re: Solve Quadratic Equation for x

Quote:
Originally Posted by pbwf
Hi

I am trying to solve the following equation for x:

8.64 = -0.0033x2 + 0.2496x + 4.2041

I'm not exactly sure how to proceed with this. Would I first subtract 8.64 from both sides so that one side can be set to 0?

Thanks

Peter
Yes
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September 11th, 2008, 02:23 PM   #3
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Re: Solve Quadratic Equation for x

Actually, there are several steps possible, each of which could be "first". If so unsure, you might want to first brush up on some simpler examples from your text. If it is allowed, I can upload a small spreadsheet I did a long time back for generating practice problems [ and answers.] It's completely free to use/change as you wish. I did a number of them on different topics just for fun.
The platform can be Excel or OpenOffice.

My own instinct would be to first multiply to get rid of decimals. My second impulse would be to rearrange to have x^2 coefficient positive. That's not critical, just force of habit just as we use rectangular coordinates at times when we really don't have to.
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September 11th, 2008, 10:15 PM   #4
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Quote:
Originally Posted by pbwf
Would I first subtract 8.64 from both sides so that one side can be set to 0?
Good idea. Then click this link. One of the roots of the equation is 47.09194..., which should suffice to verify you're doing it right, whatever method you employ.
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