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#1 2014-10-14 23:31:04

sherpa tensing
Member
Registered: 2014-04-07
Posts: 6

Surds

Hi Bobbym
The question asks for the answer to be left in surd form
I wondered if you could point me in the right direction on this quadratic equation = 3x²-4x-2=0
I used the formula -b +or -√b²-4ac divided by 2a. I got it down to   x=4 _+ 2√10 divided by 6. Now, I cancelled the 2 by 6 getting it to become  x= 4=_+ √10 divided 3, thinking this was the lowest form, I checked the answer but I was wrong.
It was given as  x= 2_+√10 divided by 3. if you can understand my reasoning and my maths, I can not for the life in me see where (b) became 2 and didn't stay as 4...........help please if you can.
Regards ST

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#2 2014-10-15 00:28:36

bobbym
bumpkin
From: Bumpkinland
Registered: 2009-04-12
Posts: 109,606

Re: Surds

Hi;

There are two roots:

For your answer of

you can just take a factor of 2 from the numerator and denominator.


In mathematics, you don't understand things. You just get used to them.
If it ain't broke, fix it until it is.
Always satisfy the Prime Directive of getting the right answer above all else.

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#3 2014-10-16 21:38:02

sherpa tensing
Member
Registered: 2014-04-07
Posts: 6

Re: Surds

Thanks Bobbym for your time.

I think I may be having a dyslexic mathematical moment. I knew there there would be 2 roots as X is squared, and can see how that comes about. I'm still slightly puzzled about "taking a factor of 2" do I just divide top and bottom by 2.......I think I'm going for a lie down in a darkened room

Regards ST

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#4 2014-10-16 21:49:11

bobbym
bumpkin
From: Bumpkinland
Registered: 2009-04-12
Posts: 109,606

Re: Surds

Hi;

You could divide the numerator and denominator by 2.


In mathematics, you don't understand things. You just get used to them.
If it ain't broke, fix it until it is.
Always satisfy the Prime Directive of getting the right answer above all else.

Offline

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