Math Is Fun Forum

Rose-Red

Guest

Square roots! Ech...

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

Re: Square roots! Ech...

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: 1,905

Re: Square roots! Ech...

-5!!!

---

IPBLE:  Increasing Performance By Lowering Expectations.

krassi_holmz

Real Member

Registered: 2005-12-02

Posts: 1,905

Re: Square roots! Ech...

Ha Ha Ha!!!

---

IPBLE:  Increasing Performance By Lowering Expectations.

krassi_holmz

Real Member

Registered: 2005-12-02

Posts: 1,905

Re: Square roots! Ech...

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.

Rose-Red

Guest

Re: Square roots! Ech...

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

krassi_holmz

Real Member

Registered: 2005-12-02

Posts: 1,905

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

---

IPBLE:  Increasing Performance By Lowering Expectations.

krassi_holmz

Real Member

Registered: 2005-12-02

Posts: 1,905

Re: Square roots! Ech...

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

---

IPBLE:  Increasing Performance By Lowering Expectations.

krassi_holmz

Real Member

Registered: 2005-12-02

Posts: 1,905

Re: Square roots! Ech...

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.

Rose-Red

Member

Registered: 2006-01-05

Posts: 19

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)

krassi_holmz

Real Member

Registered: 2005-12-02

Posts: 1,905

Re: Square roots! Ech...

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.

krassi_holmz

Real Member

Registered: 2005-12-02

Posts: 1,905

Re: Square roots! Ech...

Understand now?

---

IPBLE:  Increasing Performance By Lowering Expectations.

Rose-Red

Member

Registered: 2006-01-05

Posts: 19

Re: Square roots! Ech...

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

krassi_holmz

Real Member

Registered: 2005-12-02

Posts: 1,905

Re: Square roots! Ech...

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

---

IPBLE:  Increasing Performance By Lowering Expectations.

mathsyperson

Moderator

Registered: 2005-06-22

Posts: 4,900

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.

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.

krassi_holmz

Real Member

Registered: 2005-12-02

Posts: 1,905

Re: Square roots! Ech...

OK. I learnt something new too.

---

IPBLE:  Increasing Performance By Lowering Expectations.

Rose-Red

Member

Registered: 2006-01-05

Posts: 19

Re: Square roots! Ech...

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