Help with Maths please

Les_Rebels123

Hi,
Can anyone help me with :Surds:

I have never understood the getting of surds to their simplest form.

Question:
By rationalising the denominator,express each of the following in its simplest form:
(i)
4 over route5 + 1
(ii)
1 over route 8 - route 2

jumpguy

Haha, we're just finishing up on surds too, nice to see the country is in sync. For (i) you need to multiply the surd above and below the line by Root 5 - (MINUS) 1. You will then get a difference of 2 squares on the bottom line, and this will get rid of the root.

I won't explain number 2 to you as I don't believe in just copying your homework...and I could be wrong. But I'll explain how to do 'em.

If you are told to rationalise the denominator, look at the denominator.
Change the sign in the the MIDDLE of the denominator, if it only has 2 figures (for example, root 5 + 1, change the + in the middle to -) and multiply above and below the line by this.


NOTE I might be wrong, but I'm fairly certain. If it doesn't work out (check the answer in the back of your book) and you've performed your maths correctly I may be wrong and you'd need a second opinion.

Dmullar

Multiply above and below the fraction by the conjugate surd, which would be Root5 - 1 in the first case.

AddictedToYou

jumpguy wrote: »

Haha, we're just finishing up on surds too, nice to see the country is in sync.

Haha! Same here!:D

And I would agree with jumpguy's method..

Les_Rebels123

:D:D

Thanks for your help guys,
Its not the way i was taught(as in teached ) to do them, but this way is much easier, with the aid of a calc. that is

thank you guys again

Delta Kilo

I never really understood surds either, multiplying the conjugate was grand but I always found the others tedious. Buy a natural display calculator and it will be the best thing you will buy, they are brilliant!

eVeNtInE

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jumpguy

eVeNtInE wrote: »

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LCM is (2-Square Root 5) (2 + Square Root 5)
The LCM is the common denominator, so everything above the line goes over the LCM. You must divide the LCM by your denominators in the question which are 2 - (Square Root 5) and (2 + Square Root 5).
Next line:
4 (2 + Square Root Five) +2 (2 - Square Root Five) OVER (2-Square Root 5) (2 + Square Root 5) (that's your LCM).

You can work it out from there I'd say. The bottom line will work out to be the difference of 2 squares I think, and this will get rid of your root below the line.


It's difficult to explain over the internet, but I hope you understand it. If not, remember to ask in class! BTW how much people is in people's honours class? Only 8 in mine now.

eVeNtInE

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