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Mathematics 8 Online
OpenStudy (31356):

Factor Using Distributive Property (Check) MEDAL REWARDED!!

OpenStudy (31356):

1)x^2-7x+12 =(x-3)(x-4) right?

OpenStudy (31356):

2)x^2-16 =(x+4)(x-4) right?

OpenStudy (31356):

3)x^2-12x+36 =(x-6)(x-6) right?

OpenStudy (31356):

So it is (x-3)(x-4) right?

OpenStudy (31356):

How did you get that?

OpenStudy (whpalmer4):

Here's how you check: \[(x-3)(x-4) = x*x -4*x - 3*x + 12 = x^2 - 7x + 12\checkmark\]

OpenStudy (31356):

So it's correct? @whpalmer4

OpenStudy (whpalmer4):

That's what that big checkmark means, yes. Multiply them out carefully and compare with what you started with. If they are equal, your answer should be correct.

OpenStudy (31356):

Oh yea, forgot to read that, thanks a lot @whpalmer4 You deserve a medal! :D

OpenStudy (31356):

Do you mind if you check the rest?

OpenStudy (31356):

I have to go to a workshop later in a like a hour later.

OpenStudy (whpalmer4):

Really, you should check them yourself by multiplying them. That's how you get to be good at doing the algebra — practice! Also, it helps you recognize later when factoring how you got the results when multiplying.

OpenStudy (31356):

Okay

OpenStudy (whpalmer4):

but yes, all 3 are correct. good work!

OpenStudy (whpalmer4):

multiply them, for me :-)

OpenStudy (31356):

Can you just help me with the second one, for another example so then I will know how to do it better?

OpenStudy (whpalmer4):

and for you!

OpenStudy (31356):

Thanks!

OpenStudy (whpalmer4):

\[(x-4)(x+4) = x^x +4x -4x -16 = x^2 -16\] I don't actually multiply this when I see it, but rather recognize it as a difference of squares: \[(a+b)(a-b) = a^2-b^2\]Learn to recognize that in both directions and you'll save yourself some work over the years :-)

OpenStudy (31356):

Can you help me find the answer to this one? I am stuck on this problem. Here it is: 24^2b^2-18ab

OpenStudy (whpalmer4):

\[24^2b^2-18ab\]is that it?

OpenStudy (31356):

Thanks @whpalmer4 for showing the steps! :D

OpenStudy (31356):

Yes

OpenStudy (whpalmer4):

there's only one \(a\) in there?

OpenStudy (31356):

Wait 24a^b^2 etc..

OpenStudy (whpalmer4):

write it out exactly, please...

OpenStudy (31356):

Okay

OpenStudy (31356):

24a^2b^2-18ab

OpenStudy (whpalmer4):

one of the most valuable things learned in math class, in my opinion, is attention to detail and careful work :-)

OpenStudy (31356):

Indeed

OpenStudy (whpalmer4):

\[24a^2b^2-18ab\]and we want to factor this? Do you see any common factors?

OpenStudy (31356):

Would it be 6?

OpenStudy (whpalmer4):

we can factor out a 6, yes. what would we have after doing that?

OpenStudy (31356):

Do something with a (a & b)?

OpenStudy (whpalmer4):

no, please write out the expression after factoring out a 6...

OpenStudy (whpalmer4):

\[6(...\]

OpenStudy (31356):

Is it correct? (answer) 6(ab)

OpenStudy (whpalmer4):

Let me restate that. What do you get if you divide \(24a^2b^2-18ab\) by \(6\)?

OpenStudy (31356):

Wait for a minute or so...

OpenStudy (whpalmer4):

all you are doing is dividing the numbers in front of \(a^2b^2\) and \ab\) by 6. 24/6=? 18/6=?

OpenStudy (31356):

6(ab) I am not sure, I am confused..

OpenStudy (whpalmer4):

No, where do you get this \(6(ab)\) stuff from? Do you really not know how to divide \[\frac{24a^2b^2}{6}\] ?

OpenStudy (whpalmer4):

what is \[6*4a^2b^2\]?

OpenStudy (31356):

We just learned this unit today, so you know...

OpenStudy (31356):

24a^2 b^2?

OpenStudy (whpalmer4):

you just learned how to multiply variables and numbers together today, and you're factoring trinomials? if you say so... Yes, \[6*4a^2b^2 = 24a^2b^2\]So\[\frac{24a^2b^2}{6} = \frac{24}{6}a^2b^2 = 4a^2b^2\] What does \[\frac{18ab}{6}=\]

OpenStudy (31356):

3ab?

OpenStudy (whpalmer4):

yes! So, if we factor out a 6 from our expression, we have: \[6(4a^2b^2 - 3ab)\] Agreed? Do you see any other factors which appear in both terms of the expression in the parentheses?

OpenStudy (31356):

Yes I agree thank you! You are my lifesaver!! :D

OpenStudy (31356):

Yes a&b

OpenStudy (31356):

4-3 too?

OpenStudy (whpalmer4):

Good, \(a\) and \(b\) are both common factors. Not so good on the \(4-3\), though — does it appear in BOTH terms?

OpenStudy (31356):

Oh okay..

OpenStudy (31356):

So do we subtract the a and b exponents?

OpenStudy (whpalmer4):

Remember, the stuff in the parentheses could be written like this: \[2*2*a*a*b*b-3*a*b\] If we line them up over each other: 2*2* a*a*b*b 3*a* b The only thing both rows have in common is \(a\) and \(b\), and only one of each, right?

OpenStudy (whpalmer4):

(scanning down the columns)

OpenStudy (31356):

Yes

OpenStudy (whpalmer4):

so we can factor \(ab\) out of each term. What is \[\frac{4a^2b^2}{ab}=\]? What is \[\frac{3ab}{ab}=\]?

OpenStudy (31356):

4ab?

OpenStudy (31356):

3

OpenStudy (31356):

One's for the first and second answer

OpenStudy (whpalmer4):

good. and good. so, if we factor \(ab\) out of \(24a^2b^2-18ab\), how do we write the result?

OpenStudy (31356):

6(4ab+3)?

OpenStudy (whpalmer4):

uh, no, not quite. \[24a^2b^2-18ab = 6(4a^2b^2-3ab) = 6ab(4ab-3)\]

OpenStudy (31356):

Oh okay, thanks :D

OpenStudy (31356):

Can you help me with this one too, I am not going with variables @whpalmer4

OpenStudy (31356):

a+a^2b+a^3b^3

OpenStudy (whpalmer4):

\[a+a^2b+a^3b^3\]Do you see any common factors?

OpenStudy (31356):

No, I think

OpenStudy (whpalmer4):

No? Seriously? Doesn't \(a\) appear in each term?

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