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Mathematics 6 Online
OpenStudy (phebe):

Divide. 18x^3+12x-3x/6x^2 @mjoxprm360

OpenStudy (phebe):

do u know how to do this @mjoxprm360

OpenStudy (anonymous):

Do you know how to factor 18x^3 + 12x – 3x?

OpenStudy (phebe):

well no is it lik but lik terms toghther or something

OpenStudy (anonymous):

So, what's the greatest common factor of 18x^3 + 12x – 3x?

OpenStudy (phebe):

i think 3 am i right

OpenStudy (anonymous):

haha wait wait wait here

OpenStudy (phebe):

ok wat u fina do??

OpenStudy (anonymous):

do you know how to find the GCF? If not, I can walk you through it.

OpenStudy (anonymous):

need a walk through?

OpenStudy (phebe):

well yes i do

OpenStudy (anonymous):

Okay, so first we need to list all the prime factors of the coefficients. The coefficients are 18, 12, and 3. 3: 3 12: 2, 2, 3 18: 2, 3, 3 Now, I want you to tell me what one prime factor all of the coefficients have in common.

OpenStudy (phebe):

i know how to find the GCF

OpenStudy (anonymous):

ok they all have 3 in common i just wanted to explain why

OpenStudy (anonymous):

do you know how to factor the GCF out?

OpenStudy (anonymous):

?

OpenStudy (phebe):

yes

OpenStudy (anonymous):

ok good can you tell me what your answer for the gcf is?

OpenStudy (phebe):

yes i do know how to

OpenStudy (phebe):

3

OpenStudy (anonymous):

We need to put the GCF on the left side of a set of parenthesis. Like this: 3x( ) And now we need to figure out what to put in those parenthesis. And in order to do that, we need to figure out what we can multiply by 3x to get our original expression, 18x^3 + 12x – 3x. 3x times what equals 18x^3?

OpenStudy (phebe):

ok

OpenStudy (phebe):

so i multiply

OpenStudy (anonymous):

Dang, okay, don't be mad at me, but I think I read your question wrong. At first, we were supposed to combine the like-terms 12x and –3x which would equal 9x. 18x^3+9x. Are you okay with starting from scratch? It won't take as long this time since you understand the concepts.

OpenStudy (phebe):

i would never get mad at u

OpenStudy (phebe):

ok im okay with that

OpenStudy (anonymous):

Yay, okay! :D We have 18x^3 + 9x. We need to find the GCF of this expression, just like last time. Do you know how to do that now?

OpenStudy (phebe):

yes

OpenStudy (phebe):

the GCF is 3

OpenStudy (anonymous):

Yes, that's a factor of both of them, but not the GREATEST common factor. :D So let's list the prime factors of the coefficients, 18 and 9. 9: 3, 3 18: 2, 3, 3 They both have two 3's in common, right? We would multiply the two 3's to get the number 9. That's the first part of our GCF. Since our terms both have at least one x, we can also add the x to our GCF. So, the GCF is 9x. Does it make sense how we got that?

OpenStudy (phebe):

yess it does

OpenStudy (anonymous):

Okay, we need to put it on the left side of a set of parenthesis just like last time: 9x( ) Remember our original expression, 18x^3 + 9x. 9x times what equals 18x^3?

OpenStudy (phebe):

idk :( um. is it 3x+2

OpenStudy (anonymous):

2x^2

OpenStudy (phebe):

ohh ok

OpenStudy (phebe):

so wats the answer

OpenStudy (anonymous):

9x(2x^2+1) Now we factored out our first term (18x^3), and now for our second term (9x). In order to get 9x from 9x, we just multiply by 1, correct? So, this is our factored form of the expression: 9x(2x2∗1) That's just the numerator, though. We need to find 9x(2x2+1)6x2 The denominator (6x^2) doesn't need to be factored. Now that we have both the numerator and the denominator factored, we can begin to divide out terms. Do you know how to do that?

OpenStudy (anonymous):

You divide like terms

OpenStudy (phebe):

um........ noo but is it jus dividing the like terms

OpenStudy (anonymous):

9x(2x2+1)6x2 Do you know what the greatest common factor of 6 and 9 is? In other words, what's the greatest number than can divide into both of them?

OpenStudy (phebe):

its 3 again

OpenStudy (anonymous):

Yes! So 9÷3 is 3, and 6÷3 is 2. We can divide those out so we get: 3x(2x2+1)2x2 Do you see that both the numerator and the denominator have at least 1 "x" in them? (The numerator has 1 x, and the denominator has 2 x's.)

OpenStudy (anonymous):

That is, at least one x outside of the parenthesis

OpenStudy (phebe):

ok yea i see that

OpenStudy (anonymous):

Okay, good. So we can cancel out 1 "x" from the numerator and the denominator. 3(2x2+1)2x Since we can't divide anything else out, that would be your answer. Does it make sense how we got that?

OpenStudy (phebe):

yes it does

OpenStudy (anonymous):

great!

OpenStudy (phebe):

XD awesomee

OpenStudy (phebe):

so wats the answer

OpenStudy (anonymous):

\[3(2x ^2+1 \frac{ 2 }{ x }\]

OpenStudy (phebe):

thanx ndf u sure

OpenStudy (phebe):

wait is that the answer

OpenStudy (anonymous):

3(2x2+1)2x

OpenStudy (phebe):

ok thanx

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