# HELP with Math (10th grade)

• 10-22-2007, 06:49 PM
androidkaita
Ok, so heres a question I have:

2(square root)6 x 3(square root)2

The answer is 12(square root)3 according to the back of my txt book.

When I do it, I get 6(square root)12.

What am I doing wrong? I am multiplying the 2 and 3, then the 6 and 2
• 10-22-2007, 06:51 PM
foXtrot
Quote:

Originally Posted by androidkaita
Ok, so heres a question I have:

2(square root)6 x 3(square root)2

The answer is 12(square root)3 according to the back of my txt book.

When I do it, I get 6(square root)12.

What am I doing wrong? I am multiplying the 2 and 3, then the 6 and 2

Hint: What are the factors of 12? 4 and 3 maybe? You can figure out the rest.
• 10-22-2007, 06:53 PM
androidkaita
thanks, I think I understand it now
-= Double Post =-
ok, actually I dont understand
• 10-22-2007, 06:59 PM
FreePlay
2 sqrt(6) = 2 sqrt(4*1.5) = 4 sqrt(1.5).
4 sqrt(1.5) * 3 sqrt(2) = 4*3 sqrt(1.5*2) = 12 sqrt(3).
• 10-22-2007, 07:05 PM
androidkaita
We're not supposed to do it in decimals
• 10-22-2007, 07:10 PM
Archaemic
6*sqrt(12) = 6*sqrt(3*4) = 6*sqrt(3)*sqrt(4) = 12*sqrt(3)

Really, that's all there is to it.
• 10-22-2007, 07:14 PM
FreePlay
Quote:

Originally Posted by androidkaita
We're not supposed to do it in decimals

... in TENTH GRADE, you're not using decimals? Holy f***. Anyways...
Quote:

Originally Posted by FreePlay
2 sqrt(6) = 2 sqrt(4*[3/2]) = 4 sqrt(3/2).
4 sqrt(3/2) * 3 sqrt(2) = 4*3 sqrt([3/2]*2) = 12 sqrt(3).

Also:
Quote:

Originally Posted by Archaemic
6*sqrt(12) = 6*sqrt(3*4) = 6*sqrt(3)*sqrt(4) = 12*sqrt(3)

Really, that's all there is to it.

Except that he started with
Quote:

Originally Posted by androidkaita
2(square root)6 x 3(square root)2

;)
• 10-22-2007, 07:25 PM
androidkaita
lol thanks guys, but I didnt know my dad was coming home today from a trip, so he helped me and I get it now
• 10-22-2007, 07:31 PM
Sinfulfate
Quote:

Originally Posted by androidkaita
Ok, so heres a question I have:

2(square root)6 x 3(square root)2

The answer is 12(square root)3 according to the back of my txt book.

When I do it, I get 6(square root)12.

What am I doing wrong? I am multiplying the 2 and 3, then the 6 and 2

You can still simplify after you get that. To find the square root of a number like 12 you need to do a factor tree thing. A factor tree(in case you don't know) is when you find the factors that go into that number and end up with just prime numbers.

So for 12 the factor tree would be 12-6 x 2(this is prime circle it). 6 isn't prime so keep going 6-2 x3(both are prime circle them). So the three prime numbers you were left with are 2 3 and 2. And 2 x 3 x 2 is 12 so you simplified (square root)12 to (square root)2^2(thats 2 squared) x 3. So now you have 6(square root)2^2 x 3.

Well 2^2 is 4 and the square of 4 is 2 so that goes outside of the radical so now you have 6 x 2(square root)3. 6 x 2 is 12 and square root cant go into 3 evenly(and its prime so factor tree wont work) you are left with 12(square root)3.

Understand?
• 10-22-2007, 07:48 PM
SpiderJames
Quote:

Originally Posted by androidkaita
Ok, so heres a question I have:

2(square root)6 x 3(square root)2

The answer is 12(square root)3 according to the back of my txt book.

When I do it, I get 6(square root)12.

What am I doing wrong? I am multiplying the 2 and 3, then the 6 and 2

ill take a guess :o lets see 2^6 x 3^2 = 73?
• 10-22-2007, 08:00 PM
androidkaita
Quote:

Originally Posted by Sinfulfate
You can still simplify after you get that. To find the square root of a number like 12 you need to do a factor tree thing. A factor tree(in case you don't know) is when you find the factors that go into that number and end up with just prime numbers.

So for 12 the factor tree would be 12-6 x 2(this is prime circle it). 6 isn't prime so keep going 6-2 x3(both are prime circle them). So the three prime numbers you were left with are 2 3 and 2. And 2 x 3 x 2 is 12 so you simplified (square root)12 to (square root)2^2(thats 2 squared) x 3. So now you have 6(square root)2^2 x 3.

Well 2^2 is 4 and the square of 4 is 2 so that goes outside of the radical so now you have 6 x 2(square root)3. 6 x 2 is 12 and square root cant go into 3 evenly(and its prime so factor tree wont work) you are left with 12(square root)3.

Understand?

Yeah, thats exactly what my dad said :P I get it now, and im almost done
• 10-24-2007, 04:10 PM
FreePlay
Quote:

Originally Posted by SpiderJames
ill take a guess :o lets see 2^6 x 3^2 = 73?

I'm going to murder you.

2^6 = 64.
3^2 = 9.
2^6 x 3^2 = 576.
• 10-24-2007, 04:14 PM
Macca
Quote:

Originally Posted by FreePlay
I'm going to murder you.

2^6 = 64.
3^2 = 9.
2^6 x 3^2 = 576.

I have no idea how he got that. Considering 73 is a prime number and all.
• 10-24-2007, 04:19 PM
SpiderJames
Quote:

Originally Posted by FreePlay
I'm going to murder you.

2^6 = 64.
3^2 = 9.
2^6 x 3^2 = 576.

oops, I added instead of multiplying, but you guys should have figured that out before me :p arent you guys like 3 years older then me. cmon!
• 10-24-2007, 08:07 PM
FreePlay
I apologize for my brain not malfunctioning.