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Algebra 9 Online
OpenStudy (anonymous):

How do i simplify radical expressions?

OpenStudy (anonymous):

what radical question

OpenStudy (anonymous):

the square root of 125n

OpenStudy (anonymous):

you do 125/6 then 9*9

OpenStudy (johnweldon1993):

\[\large \sqrt{125n}\] Hint \[\large 125 = 25 \times 5\]

OpenStudy (johnweldon1993):

So we might really have \[\large \sqrt{25 \times 5 \times n}\]

OpenStudy (anonymous):

n=5 you twat

OpenStudy (anonymous):

so the answer would be...?

OpenStudy (anonymous):

5 babe dont listen to them

OpenStudy (anonymous):

so the n doesnt matter? @jeedeee

OpenStudy (johnweldon1993):

\[\large \sqrt{25 \times 5 \times n}\] the square root of 25 is 5 so we have \[\large 5\sqrt{5n}\]

OpenStudy (anonymous):

so thats the answer? hah

OpenStudy (anonymous):

the answer is 2.5 n=2.5

OpenStudy (johnweldon1993):

yeah @Mychelynn99 Idk where @jeedeee was looking...all you asked was to simplify √125n Idk where the 6 or 9*9 came from?

OpenStudy (anonymous):

sooooo the answer is 5n?

OpenStudy (johnweldon1993):

The answer would be \[\large 5\sqrt{5n}\]

OpenStudy (anonymous):

Okay thanks!

OpenStudy (johnweldon1993):

So we have \[\large \sqrt{512k^2}\] We know that \[\large 512 = 256 \times 2\] so we really have \[\large \sqrt{256 \times 2 \times k^2}\] we know that the square root of 256 = 16 so we have \[\large 16\sqrt{2 \times k^2}\] and we also know that \[\large \sqrt{k^2} = k\] so alltogether we have \[\large 16k\sqrt{2}\]

OpenStudy (johnweldon1993):

@Mychelynn99 :)

OpenStudy (anonymous):

so if i have the square root of 80p^3 the answer would be.... umm yeah i still dont fully understand @johnweldon1993

OpenStudy (johnweldon1993):

Alright no problem Alright so notice how first...I take the number (80 here) and break it up We know: 40 times 2 = 80 20 times 4 = 80 16 times 5 = 80 <--- right here is where we stop Why? because we know 16 is a perfect square...

OpenStudy (johnweldon1993):

Perfect square meaning 1^2 = 1 2^2 = 4 3^2 = 9 4^4 = 16 <--- look at that

OpenStudy (johnweldon1993):

So how does that help? Well...if we know that 80 can be broken up into 16 times 5....we can write it as \[\large \sqrt{16 \times 5 \times p^3}\]

OpenStudy (johnweldon1993):

And as we just found out....the square root of 16...is 4....since 4 squared.. 16 \[\huge \sqrt[2]{4^2} = 4\]

OpenStudy (johnweldon1993):

So now what we have....knowing that the square root of 16...is 4....is \[\large 4\sqrt{5p^3}\]

OpenStudy (johnweldon1993):

Making sense so far hun?

OpenStudy (anonymous):

kinda...

OpenStudy (johnweldon1993):

Which part is confusing? :)

OpenStudy (anonymous):

how to know to stop at 16 times 5

OpenStudy (johnweldon1993):

Oh okay.... alright firstly....we need to understand perfect squares... meaning when you square a number....(multiply it by itself) what does it equal? so for example when you square 1....(multiply 1 by itself) so \[\large 1 \times 1 = 1\] so \[\large 1^2 = 1\] does that make sense?

OpenStudy (anonymous):

yes

OpenStudy (johnweldon1993):

Great.... so if we continue on that path 2 squared would be \[\large 2^2 = 2 \times 2 = 4\] \[\large 3^2 = 3 \times 3 = 9\] \[\large 4^2 = 4 \times 4 = 16\] okay?

OpenStudy (anonymous):

Got it

OpenStudy (johnweldon1993):

Alright...so back to the original problem lets ignore the p^3 for this part... imagine we just have \[\large \sqrt{80}\] Like we said...we want to figure out if any perfect squares divide evenly into 80

OpenStudy (anonymous):

40 times 2?

OpenStudy (johnweldon1993):

We do that...because the square root....of a number squared....is the number for example... \[\large \sqrt{1^2} = 1\] \[\large \sqrt{5^2} = 5\] etc...the SQUARE root and the SQUARE cancel out..leaving us with just the number

OpenStudy (johnweldon1993):

So yes...lets list what goes into 80 evenly If we multiply 40 times 2...we get 80.....but is either 40 or 2 a perfect square? Nope...so we keep going... if we multiply 20 times 4....we get 80....now we see that 4 is indeed a perfect square \(\large 2^2 = 4\) so we CAN do that...but...we see that 20 can still be broken down a bit so we can keep going... (we CAN stop there though....but we wont :)

OpenStudy (johnweldon1993):

So lets continue now... we know that 16 times 5 = 80 ....and we want to stop here.....because we know that 16 is a perfect square \(\large 4^2 = 16\) and we can see that 5 cannot be broken down anymore...

OpenStudy (anonymous):

got it so far

OpenStudy (johnweldon1993):

Great....so lets start from the beginning.. \[\large \sqrt{80p^3}\] Now that we know 80 can be written as 16 times 5...lets write it as so... \[\large \sqrt{16 \times 5 \times p^3}\]

OpenStudy (johnweldon1993):

We just found...that 16...is a perfect square....it is \(\large 4^2 = 16\) since that is the case...we can write the 4 on the outside \[\large 4\sqrt{5p^3}\] still good?

OpenStudy (anonymous):

yupp

OpenStudy (johnweldon1993):

Great....now we focus on the \(\large p^3\) We know that \[\large p^3 = p^2 \times p\] right?

OpenStudy (anonymous):

right

OpenStudy (johnweldon1993):

So lets write that \[\large 4\sqrt{5 \times p^2 \times p}\] okay?

OpenStudy (johnweldon1993):

Remember how the square root of a squared number...is just the number? \[\large \sqrt[2]{7^2} = 7\] and \[\large \sqrt[2]{9^2} = 9\] well the same rule stands here...just imagine 'p' was a number...so \[\large \sqrt[2]{p^2} = p\] make sense?

OpenStudy (anonymous):

clear as day

OpenStudy (johnweldon1993):

Great! So just like when we wrote the 4 on the outside when we simplified \(\large \sqrt[2]{16}\) we can now write 'p' on the outside since we simplified that p^2 so altogether we have \[\large 4p\sqrt{5p}\]

OpenStudy (johnweldon1993):

And that would be our final answer there :)

OpenStudy (anonymous):

ugh this is so complicated!

OpenStudy (johnweldon1993):

What confused you there hun?

OpenStudy (anonymous):

why is there a p by the 5 too?

OpenStudy (johnweldon1993):

Well remember we had \[\large 4\sqrt{5 \times p^3}\] and we knew that \[\large p^3 = p^2 \times p\] so when we wrote tht in...we had \[\large 4\sqrt{5 \times p^2 \times p}\]

OpenStudy (johnweldon1993):

So when we simplified \(\large \sqrt{p^2}\) we do indeed get the 'p' that showed up outside the square root...but notice how we never touched that last 'p' that stays inside the square root \[\large 4p\sqrt{5p}\]

OpenStudy (anonymous):

gotcha

OpenStudy (anonymous):

sorry imm askng so much

OpenStudy (johnweldon1993):

No not at all hun :) I want to make sure you get this :)

OpenStudy (anonymous):

So..can you help me on another?

OpenStudy (johnweldon1993):

Of course :)

OpenStudy (anonymous):

the square root of 45p^2

OpenStudy (johnweldon1993):

Alright...so same thing here... what times what = 45? list anything you can think of...

OpenStudy (anonymous):

7*5

OpenStudy (anonymous):

but thats not a perfect square

OpenStudy (johnweldon1993):

\[\large 7 \times 5 \cancel{=}45\]

OpenStudy (anonymous):

LMAO blonde moment 9*5

OpenStudy (johnweldon1993):

Haha we all have em ;P Okay....good :) ....now...does that have a perfect square?

OpenStudy (anonymous):

nope

OpenStudy (johnweldon1993):

.....sure? ... :) hint* \[\large 3^2 = ?\]

OpenStudy (anonymous):

ohh 3*3=9

OpenStudy (johnweldon1993):

Mmhmm :) so we know that 9 is a perfect square :) \[\large \sqrt{45p^2}\] we found that 45 can be written as 9 times 5 so \[\large \sqrt{9 \times 5 \times p^2}\] And we just saw that 9 is \(\large 3^2\) so we write that 3 on the outside like before... \[\large 3\sqrt{5p^2}\] making sense?

OpenStudy (anonymous):

makes sense. I think im finally catching on. omg but how would i do square root of 28x^3y^3

OpenStudy (johnweldon1993):

Focus on 1 part at a time :) the 28 part...what times what = 28?

OpenStudy (anonymous):

7 times 4

OpenStudy (anonymous):

so it would be 7*4*x^3*y^3?

OpenStudy (johnweldon1993):

RIGHT :) so we have that \[\large \sqrt{7 \times 4 \times x^3 \times y^3}\] wheres the perfect square?

OpenStudy (anonymous):

4 2*2

OpenStudy (johnweldon1993):

Right! :D good you are getting it :D so write that 2 on the outside... \[\large 2\sqrt{7 \times x^3 \times y^3}\] remember before...how we knew that \(\large p^3 = p^2 \times p\) ?

OpenStudy (anonymous):

im kinda lost

OpenStudy (johnweldon1993):

Where hun?

OpenStudy (anonymous):

the p hah

OpenStudy (johnweldon1993):

lol I was just bringing up that last problem... where we had \[\large p^3\] and we knew we can write that as \[\large p^2 \times p\]

OpenStudy (anonymous):

oh yeah haha

OpenStudy (johnweldon1993):

Alright lol so here we have that same thing...but we have \[\large x^3\] and \[\large y^3\] so those can be written as ?

OpenStudy (anonymous):

so x^2*x?

OpenStudy (johnweldon1993):

Mmhmm...anddddddd (the 'y' one now :)

OpenStudy (anonymous):

y^2*y

OpenStudy (johnweldon1993):

Great! Alltogether we have \[\large 2\sqrt{7 \times x^2 \times x \times y^2 \times y}\] right?

OpenStudy (anonymous):

Right

OpenStudy (johnweldon1993):

Now remember what happened last time? \[\large \sqrt[2]{p^2} = p\] sooo here when we simplify both the x^2 and the y^2...we get?

OpenStudy (anonymous):

umm not sure

OpenStudy (johnweldon1993):

well it would be the same thing that happened before....I was bringing that 'p' there again to show what happened... since we knew that √p^2 became p we know that √x^2 will be x and that √y^2 will be y right?

OpenStudy (anonymous):

oh psh duh okay so x^2 would be x, right? and same with y

OpenStudy (johnweldon1993):

Mmhmm..so lets catch up...we had \[\large 2\sqrt{7 \times x^2 \times x \times y^2 \times y}\] and now we know...when we simplify the x^2 and the y^2...we will have an 'x' and a 'y' on the outside again....but remember...we never touch the other x and the other y that are in there... so alltogether we have \[\large 2xy \sqrt{7xy}\]

OpenStudy (anonymous):

alrighty

OpenStudy (johnweldon1993):

But...does that make sense?

OpenStudy (anonymous):

yes

OpenStudy (johnweldon1993):

Awesome :)

OpenStudy (johnweldon1993):

Feel free to message me if you need any more help :)

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