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Mathematics 13 Online
OpenStudy (anonymous):

Simplify 5√3•4√3=

OpenStudy (danjs):

string of multiplication \[5 * \sqrt{3} * 4 * \sqrt{3}\]

OpenStudy (anonymous):

And

OpenStudy (danjs):

remember a square root is the same as raised to 1/2 power root 3 times root 3 will cancel the square root, \[\large \sqrt{x}*\sqrt{x} = [\sqrt{x}]^2 = x^{(1/2)*2} = x\]

OpenStudy (danjs):

so you just get 5 * 4 * 3

OpenStudy (anonymous):

OH so that's all

OpenStudy (anonymous):

How about this one √8•6√5

OpenStudy (anonymous):

DanJs can you please help me with the rest

OpenStudy (danjs):

yeah, you can combine those roots since they are multiplied 6*root(8*5) 6* root(40) simplify the root 40

OpenStudy (anonymous):

How do I simplify root 40

OpenStudy (danjs):

6* root(4 * 10) = 6* root(4) * root(10) = 6 * 2 * root 10 12*root(10)

OpenStudy (danjs):

break it up into any squares it may contain , here 4 * 10 = 2^2 * 10,

OpenStudy (danjs):

you can pull that 2 out front root 2^2 = 2

OpenStudy (danjs):

break the numbers into their prime factors, and take out any perfect squares you can, if any

OpenStudy (anonymous):

Thank you I also have two more I really don't understand anything about roots

OpenStudy (anonymous):

If u can help with these

OpenStudy (retireed):

To make the first equation simpler to understand, let ignore the root by letting x=root(5) What would the answer be for 3x+ 11x-x ?

OpenStudy (anonymous):

14x-x

OpenStudy (retireed):

yes but what is 14x - 1x ?

OpenStudy (anonymous):

13x

OpenStudy (retireed):

correct now recall x = root(5) so substitute x back into your equation to get the final answer

OpenStudy (anonymous):

How do I do that

OpenStudy (retireed):

where you see an x, replace it with a root(5)

OpenStudy (anonymous):

So is my answer 13√5

OpenStudy (retireed):

a simpler way to do the first equation is to factor out the root(5) such that 3root(5) + 11root(5) - root(5) = (3 +11 -1)root(5) = 13root(5)

OpenStudy (retireed):

yes

OpenStudy (anonymous):

Ok thank you so much what about the second equation

OpenStudy (retireed):

simplify the first two terms and way DanJS showed you and sum the terms. Look for a common root for all three terms.

OpenStudy (anonymous):

I don't get it

OpenStudy (anonymous):

Root 3

OpenStudy (retireed):

break the numbers into their prime factors, and take out any perfect squares you can, if any per DanJS

OpenStudy (anonymous):

I don't know how to break the numbers into their prime factors

OpenStudy (retireed):

do you know what prime factors are?

OpenStudy (anonymous):

Yeah I do but what about the 3

OpenStudy (retireed):

3 is a prime number

OpenStudy (anonymous):

So what's next

OpenStudy (retireed):

In number theory, the prime factors of a positive integer are the prime numbers that divide that integer exactly.

OpenStudy (retireed):

What are the prime factors for 12?

OpenStudy (anonymous):

2 6 2 3

OpenStudy (retireed):

Your close what are the prime factors of 6 ?

OpenStudy (anonymous):

2 3

OpenStudy (retireed):

Yes, so the prime factor of 12 is 2, 2 and 3 such that if I take 2 x 2 x 3 I get 12. This is the same as 2^2 x 3 = 12 break the numbers into their prime factors, and take out any perfect squares you can, if any per DanJS The perfect square is the 2^2 or 4

OpenStudy (anonymous):

So what's my final answer

OpenStudy (retireed):

so to simplify root(12) = root(4) times root(3) the square root of 4 is 2 so root(12) is 2root(3) Now you have to simplify root(27) by the same method then add all 3 terms with the common root

OpenStudy (anonymous):

Can you demonstrate it please

OpenStudy (retireed):

figure out the prime factors in 27 find a perfect square and add the terms

OpenStudy (anonymous):

27 9 3 3 3

OpenStudy (danjs):

yes, when you are adding together terms containing roots, the stuff under the root has to be the same you cant add root(2) to root(5) for example,

OpenStudy (danjs):

so really you may not be able to simplify at all maybe, follow what you did with the factoring first

OpenStudy (danjs):

\[\sqrt{12}=\sqrt{3*4}=\sqrt{3*2*2} = \sqrt{3*2^2} = \sqrt{3}*\sqrt{2^2} = 2*\sqrt{3}\]

OpenStudy (danjs):

27 = 9 * 3 = 3 * 3 * 3 = 3^2 * 3 root(27) = root(3^2)*root(3) = 3*root 3

OpenStudy (danjs):

all are multiples of root 3 now, you can total them up

OpenStudy (anonymous):

So what's my answer going to be

OpenStudy (danjs):

\[2\sqrt{3}-3\sqrt{3}+\sqrt{3}\] 2 -3 + 1 or 0*root(3) = 0

OpenStudy (danjs):

simplifies to zero

OpenStudy (anonymous):

Yeah so what do I write

OpenStudy (anonymous):

Just zero

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