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# Surds

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1. Surds
can some1 please explain to me how you would solve
sqrt45 + 20/sqrt5

Sqrt=square root
2. Re: Surds
(Original post by bahjat93)
can some1 please explain to me how you would solve
sqrt45 + 20/sqrt5

Sqrt=square root

Remember,
3. Re: Surds
(Original post by raheem94)

Remember,
i got that far but i couldn't go any further then that .
This is the only question i'm stuck on in the ENTIRE exam paper
4. Re: Surds
I would rationalise the denominator... If that makes sense...
5. Re: Surds
(Original post by bahjat93)
i got that far but i couldn't go any further then that .
This is the only question i'm stuck on in the ENTIRE exam paper

Can you now do it?
Last edited by raheem94; 08-05-2012 at 20:51.
6. Re: Surds
(Original post by Booyah)
I would rationalise the denominator... If that makes sense...
7. Re: Surds
do the cross and smile technique. sqrt45 = sqrt45/1
Multiply the denominators together. Multiply each numerator with the opposite denominator. Add them together. So (sqrt45*sqrt5 + 20)/sqrt5
(sqrt9*sqrt5*sqrt5 +20)/sqrt5
=(3*5+20)/sqrt5
=(15+20)/sqrt5
=35/sqrt5
8. Re: Surds
(Original post by bahjat93)

So you would multiply 20/5^1/2 by( 5^1/2 ) / ( 5^1/2 )
9. Re: Surds
(Original post by Rainingshame)
do the cross and smile technique. sqrt45 = sqrt45/1
Multiply the denominators together. Multiply each numerator with the opposite denominator. Add them together. So (sqrt45*sqrt5 + 20)/sqrt5
(sqrt9*sqrt5*sqrt5 +20)/sqrt5
=(3*5+20)/sqrt5
=(15+20)/sqrt5
=35/sqrt5
another question, how would you turn
35/sqrt5 into 7sqrt5 ???
10. Re: Surds
(Original post by bahjat93)
another question, how would you turn
35/sqrt5 into 7sqrt5 ???
Multiply the numerator and denominator by and see what cancels.
11. Re: Surds
(Original post by nuodai)
Multiply the numerator and denominator by and see what cancels.
Ty, i just realised i was being an idiot :/, i thought multiplying the denominator and the numerator by sqrt 5 would cancel the sqrt 5 at the bottom but i see the error of my ways now.

Good luck on your exam guys
12. Re: Surds
sqrt45 = 3sqrt5
therefore, sqrt45+20sqrt5 = 3sqrt5+20sqrt5 = 23sqrt5
13. Re: Surds
sqrt45 = 3sqrt5
therefore, sqrt45+20sqrt5 = 3sqrt5+20sqrt5 = 23sqrt5
Number 1: Don't post full solutions
Number 2: That solution is wrong. It is (20sqrt5)/5 = 4 sqrt5
14. Re: Surds
(Original post by raheem94)

Can you now do it?
can you show me the full working out to this question
15. Re: Surds
(Original post by zed963)
can you show me the full working out to this question

Done.

Do you understand it?
16. Re: Surds
(Original post by raheem94)

Done.

Do you understand it?
Not exactly were have u got 3root5 root 5 from
17. Re: Surds
(Original post by raheem94)

Done.

Do you understand it?
This is what I would do.
Attached Thumbnails

18. Re: Surds
(Original post by steve2005)
This is what I would do.
Good explanation.

Can you give me a question like that.
19. Re: Surds
(Original post by steve2005)
This is what I would do.
20. Re: Surds
(Original post by raheem94)
Can u give me a question like that

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Last updated: May 9, 2012
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