Discussion about math, puzzles, games and fun. Useful symbols: ÷ × ½ √ ∞ ≠ ≤ ≥ ≈ ⇒ ± ∈ Δ θ ∴ ∑ ∫ π -¹ ² ³ °

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**Rose-Red****Guest**

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

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

**Rose-Red****Guest**

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

**krassi_holmz****Real Member**- Registered: 2005-12-02
- Posts: 1,906

-5!!!

IPBLE: Increasing Performance By Lowering Expectations.

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**krassi_holmz****Real Member**- Registered: 2005-12-02
- Posts: 1,906

Ha Ha Ha!!!

IPBLE: Increasing Performance By Lowering Expectations.

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**krassi_holmz****Real Member**- Registered: 2005-12-02
- Posts: 1,906

Good question!

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

*Last edited by krassi_holmz (2006-01-05 09:23:28)*

IPBLE: Increasing Performance By Lowering Expectations.

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**Rose-Red****Guest**

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

**krassi_holmz****Real Member**- Registered: 2005-12-02
- Posts: 1,906

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 (2006-01-05 09:35:31)*

IPBLE: Increasing Performance By Lowering Expectations.

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**krassi_holmz****Real Member**- Registered: 2005-12-02
- Posts: 1,906

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

IPBLE: Increasing Performance By Lowering Expectations.

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**krassi_holmz****Real Member**- Registered: 2005-12-02
- Posts: 1,906

Like this:

` [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.

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**Rose-Red****Member**- Registered: 2006-01-05
- Posts: 19

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)

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**krassi_holmz****Real Member**- Registered: 2005-12-02
- Posts: 1,906

This means "power" here is it:

(this is the thin moment:)

√(9 - 4√5) = √(9 - 2.2.√5) = √((2²+√5²) - 2.2.√5) = √((2-√5)²) = |2-√5| = √5-2. Substituting:

√(9-4√5)-3-√5 = √5-2-3-√5=-5

answer:-5

IPBLE: Increasing Performance By Lowering Expectations.

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**krassi_holmz****Real Member**- Registered: 2005-12-02
- Posts: 1,906

Understand now?

IPBLE: Increasing Performance By Lowering Expectations.

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**Rose-Red****Member**- Registered: 2006-01-05
- Posts: 19

Thanx alot, I've been solving this for the whole week. Now its very clear. Making 9 into 2²+√5² was very new for me. Learning everyday. Hehe

thanx again

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**krassi_holmz****Real Member**- Registered: 2005-12-02
- Posts: 1,906

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

IPBLE: Increasing Performance By Lowering Expectations.

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**mathsyperson****Moderator**- Registered: 2005-06-22
- Posts: 4,900

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

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

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

Why did the vector cross the road?

It wanted to be normal.

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**krassi_holmz****Real Member**- Registered: 2005-12-02
- Posts: 1,906

OK. I learnt something new too.

IPBLE: Increasing Performance By Lowering Expectations.

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**Rose-Red****Member**- Registered: 2006-01-05
- Posts: 19

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

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