Transforming an alg...
 

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[Closed] Transforming an algebraic expression - help

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OK, I have a long calculation involving logarithms for my HNC which is presenting me with no real dramas.

I got to a stage and for the life of me I cannot figure out why (1-2x) x 0.1875 transforms to 0.1875 - 0.375x

I'm assuming its a simply step but it really is doing my head in.

Ta 🙂


 
Posted : 17/10/2012 12:41 pm
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what's on the other side of the = sign?


 
Posted : 17/10/2012 12:43 pm
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multiply out the bracket components and the factor:

(1-2x) X 0.1875 is the same as
1 X 0.1875 + -2 X x X 0.1875

which is 0.1875 - 0.375 X x


 
Posted : 17/10/2012 12:45 pm
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Same as 0.1875 (1 - 2x) no?

i.e. 0.1875 - 0.375x


 
Posted : 17/10/2012 12:47 pm
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OK full expression is (1.2x) x 0.1875 - 0.6355x = 0.1153

Which then transforms to 0.1875 - 0.375x - 0.6355x = 0.1153


 
Posted : 17/10/2012 12:47 pm
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@stoner has it (first) as does @rocketman

I think you've just over-thought it and confused yourself, from what you say you've done the hard part


 
Posted : 17/10/2012 12:48 pm
 IHN
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(1-2x)x 0.1875 = (1 x 0.1875) - (2x x 0.1875)

= 0.1875 - 0.375x


 
Posted : 17/10/2012 12:48 pm
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0.1875 - 0.375x - 0.6355x = 0.1153

...

-1.0105x = -0.0722

x = 0.07145


 
Posted : 17/10/2012 12:50 pm
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Stoner, explained simply. Thanks all

I'm tackling this HNC after 16 years of doing no real maths . So sometimes find basic problem solving becomes a nightmare. I have tutors to ask but as I m doing it distance learning its actually quicker and easier to look n the net or obviously just ask the many on here. It really is appreciated 🙂


 
Posted : 17/10/2012 12:52 pm
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For fun you could also go to www.wolframalpha.com and type
'solve (1-2x) * 0.1875 - 0.6355x= 0.1153'
into the search line.

It will give you the answer but then if you click on 'step by step solution' on the right it gives a fantastic breakdown.

It's definitely the go-to search engine when you want a number (e.g. population of N.Korea) rather than just text


 
Posted : 17/10/2012 1:03 pm
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Thanks, that's been pointed out to me a few times. I'll check it out later 🙂


 
Posted : 17/10/2012 1:11 pm
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If you want to see what the explanation would look like for your example I've posted it [url= https://picasaweb.google.com/lh/photo/X_Zv785lLxN6utKGfXC_LQ5-DRgwL3Nx7wbff-LYT-Q?feat=directlink ]here[/url]

You are probably best to download the picture to look at it as it is tall and thin and doesn't seem to zoom well on t'web


 
Posted : 17/10/2012 1:13 pm
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Leffeboy, thanks for putting that effort in. had a good look at it and it all makes sense. Im finding the gaps in my knowledge are the simple things 🙂


 
Posted : 17/10/2012 3:04 pm
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I really enjoyed that; anyone recommend a book if I wanted to get back into maths for fun?, got an A at GCSE but that was 23 years ago


 
Posted : 17/10/2012 3:33 pm
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Ben, that's probably the dullest part of maths ever!!! Try 'You are a Mathematician' for some much more wow stuff.

http://www.amazon.co.uk/gp/aw/d/014017480X/ref=mp_s_a_1?pi=SL75&qid=1350489025&sr=8-1


 
Posted : 17/10/2012 3:51 pm
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Leffeboy, thanks for putting that effort in. had a good look at it and it all makes sense

Just to be clear it wasn't me that did that - that's the output from Wolfram Alpha, it's really rather nice. All I did was post the pic online


 
Posted : 17/10/2012 6:35 pm
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Ah cool, i tried to get Wolfram Alpha to display the full workings but i had to pay a monthly fee. I might see if its worth it down the line 🙂


 
Posted : 17/10/2012 6:38 pm
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have you been using youtube

some great videos on all kinds of maths


 
Posted : 17/10/2012 6:43 pm
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I really enjoyed that; anyone recommend a book if I wanted to get back into maths for fun?, got an A at GCSE but that was 23 years ago

Books are old school. Try Khan Academy: http://www.khanacademy.org

Video lectures, interactive learning, tests and achievements.
It's ace for everything from basic arithmetic to astrophysics.


 
Posted : 17/10/2012 6:46 pm
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Yea, i mainly use the Khan Academy website and YouTube for picking up information. Like i said i have some pretty obvious gaps in my knowledge due to the amount of time since i left school until now, but the internet is a phenomenal tool with a lot of resources to help.


 
Posted : 17/10/2012 6:46 pm
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Ah cool, i tried to get Wolfram Alpha to display the full workings but i had to pay a monthly fee

You can do something like 3 sets of free workings each day. I just logged in using my facebook account and it seemed to all work.


 
Posted : 17/10/2012 7:44 pm

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