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Mathematics 17 Online
OpenStudy (anonymous):

Simplifying Radicals, HELP PLEASE?

OpenStudy (anonymous):

1) Sqr. Root of 96 2) 8square root of 63x^5 3) Sqr. Root of 128x^5y^2 4) power of 3 sqr. root of 32 5) power of 3 sqr. root of 56x^14

OpenStudy (anonymous):

Please do not write in decimal form.. Thank you :D

jimthompson5910 (jim_thompson5910):

Can you factor 96 into two numbers were one of those numbers is a perfect square?

OpenStudy (anonymous):

Yes??? Idk.

jimthompson5910 (jim_thompson5910):

ok give it your best shot and show me what you think it is

OpenStudy (anonymous):

I don't know how to do it... Can you tell me how?

jimthompson5910 (jim_thompson5910):

the list of perfect squares are 1, 4, 9, 16, 25, 49, 64, 81, 100, .. and this list goes on

jimthompson5910 (jim_thompson5910):

look familiar?

jimthompson5910 (jim_thompson5910):

oops meant to say 1, 4, 9, 16, 25, 36, 49, 64, 81, 100, ..

jimthompson5910 (jim_thompson5910):

which of these numbers is a factor of 96?

jimthompson5910 (jim_thompson5910):

no, just a factor

OpenStudy (anonymous):

Um.. 1, 4, 16,

jimthompson5910 (jim_thompson5910):

good, the largest factor in that list is 16

jimthompson5910 (jim_thompson5910):

now divide 96 by 16 to get 96/16 = ???

OpenStudy (anonymous):

6

jimthompson5910 (jim_thompson5910):

so 96 is the same as 16*6

jimthompson5910 (jim_thompson5910):

since 96 = 16*6

jimthompson5910 (jim_thompson5910):

so this allows us to go from \[\Large \sqrt{96}\] to \[\Large \sqrt{16*6}\]

jimthompson5910 (jim_thompson5910):

Afterwards, we break up the square root to get \[\Large \sqrt{16}*\sqrt{6}\]

OpenStudy (anonymous):

Okay. Is that it?

jimthompson5910 (jim_thompson5910):

not quite there though

jimthompson5910 (jim_thompson5910):

can we simplify \(\Large \sqrt{16}\) ??

OpenStudy (anonymous):

4?

jimthompson5910 (jim_thompson5910):

good, so in the end, \[\Large \sqrt{96} = 4\sqrt{6}\]

OpenStudy (anonymous):

whoah whoah whoah.... what?

jimthompson5910 (jim_thompson5910):

where are you lost

OpenStudy (anonymous):

Why does the 4 go in front of the |dw:1351199926078:dw|

jimthompson5910 (jim_thompson5910):

here are the full steps \[\Large \sqrt{96} = \sqrt{16*6}\] \[\Large \sqrt{96} = \sqrt{16}*\sqrt{6}\] \[\Large \sqrt{96} = 4\sqrt{6}\]

jimthompson5910 (jim_thompson5910):

notice how we factored, broke up the root, then simplified any roots we could

OpenStudy (anonymous):

Oh wait.. Nevermind. I get it! Thank you :) Will you help me with the rest as well, please?

jimthompson5910 (jim_thompson5910):

How about I show you how to do #2 and you show me how to do #3 (so you can show me that you have an idea of what's going on). Sound good?

OpenStudy (anonymous):

Okay :) Thank you!

OpenStudy (anonymous):

2) 8√(63x^5)

jimthompson5910 (jim_thompson5910):

The same basic rule applies as before. We need to factor each expression where one of the factors is a perfect square. So 63 = 9*7 (9 is the largest perfect square factor) for x^5, we can rewrite/factor it to get x^2*x^2*x This means... \[\Large 8\sqrt{63x^5} = 8\sqrt{9*7x^2*x^2*x}\] \[\Large 8\sqrt{63x^5} = 8\sqrt{9}*\sqrt{7}*\sqrt{x^2}*\sqrt{x^2}*\sqrt{x}\] \[\Large 8\sqrt{63x^5} = 8*3*\sqrt{7}*x*x*\sqrt{x}\] \[\Large 8\sqrt{63x^5} = 24x^2\sqrt{7x}\]

jimthompson5910 (jim_thompson5910):

The big difference is that variables are now involved, but the same basic idea applies

OpenStudy (anonymous):

I'm confused on the x^5 part.

jimthompson5910 (jim_thompson5910):

x*x = x^2 right?

OpenStudy (anonymous):

yes??

jimthompson5910 (jim_thompson5910):

well x^2 times x^2 = x^4 and x^2 times x^2 times x = x^5

jimthompson5910 (jim_thompson5910):

so that shows us that x^5 factors to x^2*x^2*x

OpenStudy (anonymous):

oooh, okay. sometimes i need to see it in word form to know what's going on, lol.

jimthompson5910 (jim_thompson5910):

i gotcha, well the star symbol * means "times"

OpenStudy (anonymous):

so, give me a minute to figure this out real quick & see if i understand...

jimthompson5910 (jim_thompson5910):

2*3 = 2 times 3

jimthompson5910 (jim_thompson5910):

ok

OpenStudy (anonymous):

why is that last part 24x^2 sqr. root 7x??

OpenStudy (anonymous):

How do you know which x's go where & how many?

jimthompson5910 (jim_thompson5910):

because I multiplied all the terms outside the root

jimthompson5910 (jim_thompson5910):

8*3 =24

jimthompson5910 (jim_thompson5910):

x*x = x^2

OpenStudy (anonymous):

I know.. but why do they go there & not by the 7?

jimthompson5910 (jim_thompson5910):

all the terms inside the roots are multiplied and combined under one single root

OpenStudy (anonymous):

why is it not 7x^3 ?

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