Algebra Question (Trying to help Daughter-in-law)

Dinger

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Thu Oct-09-08 09:46 PM
Original message

Algebra Question (Trying to help Daughter-in-law)

Edited on Thu Oct-09-08 09:47 PM by Dinger

I'm rusty as hell, and I want to help her out. Here is the problem:

How do you factor: 3x squared - x -3 ?

Thanks. She has about one hour to get this done, we're almost there. I helped her with a few other problems, but this one has me stumped. Maybe it's prime?

I know it starts like this:

(3x ) (x )

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fortyfeetunder

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Thu Oct-09-08 09:52 PM
Response to Original message

1. I sent you a PM

Hope this helps

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rurallib

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Thu Oct-09-08 10:07 PM
Response to Reply #1

2. could you write it out. I will be working with mentees on this soon

and I am rusty also.

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Dinger

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Thu Oct-09-08 10:15 PM
Response to Reply #2

3. Is It Prime?

Edited on Thu Oct-09-08 10:15 PM by Dinger

Then it can't be factored. My daughter-in-law has 3 chances to submit answers, and she has used 2. One she submitted was that it was prime, but that was incorrect.

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LisaL

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Thu Oct-09-08 11:28 PM
Response to Reply #3

8. No it's not prime.

But there are no integer solutions.
Try this:
http://www.1728.com/quadratc.htm

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pokerfan

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Fri Oct-10-08 12:11 AM
Response to Reply #8

9. The minimum is +1/6

if that helps the OP.

d/dx = 6x-1 = 0
x = 1/6

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Dinger

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Thu Oct-09-08 10:25 PM
Response to Original message

4. Still Trying . . .

& trying . . . .

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madinmaryland

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Thu Oct-09-08 10:28 PM
Response to Original message

5. 3x2 * (-3) = -9x2

:shrug:

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Lethe

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Thu Oct-09-08 10:47 PM
Response to Original message

6. using the quadratic, you get

(x - 1.1805)(x + 0.84713)

not sure if that helps or not

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pokerfan

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Thu Oct-09-08 11:20 PM
Response to Original message

7. I see no integer factors

Edited on Thu Oct-09-08 11:22 PM by pokerfan

you need two numbers that multiply to -3 and sum to -1 when one is multiplied by 3

(-3, 1) and (3, -1) both fit the first criteria but neither fit the second.

I see no simple integer solution so use the quadratic as ikhor suggested.

:shrug:

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