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  Discussion about math, puzzles, games and fun.   Useful symbols: √ ∞ ≠ ≤ ≥ ≈ ⇒ ∈ Δ θ ∴ ∑ ∫ π -

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#1 2006-01-06 07:50:45

Rose-Red
Guest

Square roots! Ech...

This is the most difficult topic for me. I'm stucked in one task.

http://img281.imageshack.us/img281/7184/dring9ew.jpg

could you help me to solve it? I know the answer, I need the whole solution

#2 2006-01-06 07:52:06

Rose-Red
Guest

Re: Square roots! Ech...

Sorry there is only the link to the image. Wasn't able to post a picture

#3 2006-01-06 08:14:36

krassi_holmz
Real Member

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Re: Square roots! Ech...

-5!!!


IPBLE:  Increasing Performance By Lowering Expectations.

#4 2006-01-06 08:19:27

krassi_holmz
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Re: Square roots! Ech...

Ha Ha Ha!!!


IPBLE:  Increasing Performance By Lowering Expectations.

#5 2006-01-06 08:21:55

krassi_holmz
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Re: Square roots! Ech...

Good question!

I'll tell you how. First, the original:

Last edited by krassi_holmz (2006-01-06 08:23:28)


IPBLE:  Increasing Performance By Lowering Expectations.

#6 2006-01-06 08:25:57

Rose-Red
Guest

Re: Square roots! Ech...

yes, the answer is -5, but I would like to know how you did that.

#7 2006-01-06 08:34:47

krassi_holmz
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Re: Square roots! Ech...

3-2√5<0 so we can remove that modulus like that:
√(9-4√5)+2√5-3-3√5 =
= √(9-4√5)-3-√5 =
(this is the thin moment:)
√(9 - 4√5) = √(9 - 2.2.√5) = √((2^2+√5^2) - 2.2.√5) = √((2-√5)^2) = |2-√5| = √5-2. Substituting:

√(9-4√5)-3-√5 = √5-2-3-√5=-5

answer:-5

Last edited by krassi_holmz (2006-01-06 08:35:31)


IPBLE:  Increasing Performance By Lowering Expectations.

#8 2006-01-06 08:36:45

krassi_holmz
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Re: Square roots! Ech...

And the tag is not [img]. It's [url].


IPBLE:  Increasing Performance By Lowering Expectations.

#9 2006-01-06 08:38:04

krassi_holmz
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Re: Square roots! Ech...

Like this:

Code:

 [url]http://img281.imageshack.us/img281/7184/dring9ew.jpg[/url]

Which gives:
http://img281.imageshack.us/img281/7184/dring9ew.jpg


IPBLE:  Increasing Performance By Lowering Expectations.

#10 2006-01-06 08:47:28

Rose-Red
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Re: Square roots! Ech...

hey this is weird.
I understand everything till that 'thin moment'
first of all what the '^' mean? is it multiplying or what?
then where did you get √((2^2+√5^2)

#11 2006-01-06 08:50:50

krassi_holmz
Real Member

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Re: Square roots! Ech...

This means "power" here is it:

(this is the thin moment:)
√(9 - 4√5) = √(9 - 2.2.√5) = √((2+√5) - 2.2.√5) = √((2-√5)) = |2-√5| = √5-2. Substituting:

√(9-4√5)-3-√5 = √5-2-3-√5=-5

answer:-5


IPBLE:  Increasing Performance By Lowering Expectations.

#12 2006-01-06 08:52:00

krassi_holmz
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Re: Square roots! Ech...

Understand now?


IPBLE:  Increasing Performance By Lowering Expectations.

#13 2006-01-06 08:57:30

Rose-Red
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Re: Square roots! Ech...

Thanx alot, I've been solving this for the whole week. Now its very clear. Making 9 into 2+√5 was very new for me. Learning everyday. Hehe

thanx again smile

#14 2006-01-06 08:59:56

krassi_holmz
Real Member

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Re: Square roots! Ech...

If you wave another "weekly" problem, you may post it.


IPBLE:  Increasing Performance By Lowering Expectations.

#15 2006-01-07 04:18:12

mathsyperson
Moderator

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Re: Square roots! Ech...

It looks like krazzi has beaten me to the maths help, so I'll just help with the BB Code instead. smile

The tag is [img], it's just that you need a slash when you close it.

Code:

[img]http://img281.imageshack.us/img281/7184/dring9ew.jpg[/img]

Why did the vector cross the road?
It wanted to be normal.

#16 2006-01-07 04:19:46

krassi_holmz
Real Member

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Re: Square roots! Ech...

OK. I learnt something new too.


IPBLE:  Increasing Performance By Lowering Expectations.

#17 2006-01-07 09:00:04

Rose-Red
Member

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Re: Square roots! Ech...

oh, I knew I did it right, but just missed that slash

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