# factor

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• Dec 8th 2009, 09:09 AM
taemonique
factor
3v^3-192

factor completely
• Dec 8th 2009, 09:11 AM
TheEmptySet
Quote:

Originally Posted by taemonique
3v^3-192

factor completely

Factor out a 3 from each term, then use the difference of cubes formula

$3(v^3-64)$

remember that

$a^3-b^3=(a-b)(a^2+ab+b^2)$
• Dec 8th 2009, 09:13 AM
taemonique
so what is the answer? because that isnt factored completely(Doh)
• Dec 8th 2009, 09:16 AM
doomgaze
Quote:

Originally Posted by taemonique
so what is the answer? because that isnt factored completely(Doh)

use the formula he gave you, you want to learn how to do it not just get the answer.
• Dec 8th 2009, 09:19 AM
taemonique
i did that much already. I dont see how to completly fctor it out
• Dec 8th 2009, 11:40 AM
manhmanh17vn
$3V^3-192=3(V^3-64)=3(V^3-4^3)=?$
use this :http://www.mathhelpforum.com/math-he...a6b5924a-1.gif
and finish this by yourself.
• Dec 8th 2009, 11:47 AM
Mukilab
Forgive me if I am incorrect. Not completely sure with factorising but I chanced upon this.

Without using the $4^3$ but using the technique showed I got

$3v^3-192=...$then $(3v-64)(3v^2+(3v*64)+64^2)$
• Dec 8th 2009, 11:53 AM
manhmanh17vn
Quote:

Originally Posted by Mukilab
Forgive me if I am incorrect. Not completely sure with factorising but I chanced upon this.

Without using the $4^3$ but using the technique showed I got

$3v^3-192=...$then $(3v-64)(3v^2+(3v*64)+64^2)$

this is incorrect. you need think against.(Crying)
• Dec 8th 2009, 11:58 AM
Mukilab
Probably because I didn't account for the $4^3$

Can you account for my mistake?

I'll try again

$3v^3-192=....$then $(3v-4^3)(3v^2+(3v4^3)+4^6)$

• Dec 8th 2009, 12:02 PM
mr fantastic
Quote:

Originally Posted by Mukilab
Probably because I didn't account for the $4^3$

Can you account for my mistake?

I'll try again

$3v^3-192=....$then $(3v-4^3)(3v^2+(3v4^3)+4^6)$

You have been told exactly what to do. Go back. Read post #2. For your question, what is a? What is b? Substitute. Get the answer.
• Dec 8th 2009, 12:09 PM
Mukilab
Finally?

http://www.mathhelpforum.com/math-he...c0888190-1.gif $\Rightarrow 3v^3-192$

http://www.mathhelpforum.com/math-he...a6b5924a-1.gif

$3v^9-64^9 \Rightarrow = (3v^3-64^3)(3v^6+3v^3(-64^3)-64^6)$
• Dec 8th 2009, 12:14 PM
mr fantastic
Quote:

Originally Posted by Mukilab
Finally?

http://www.mathhelpforum.com/math-he...c0888190-1.gif $\Rightarrow 3v^3-192$

http://www.mathhelpforum.com/math-he...a6b5924a-1.gif

$3v^9-64^9 \Rightarrow = (3v^3-64^3)(3v^6+3v^3(-64^3)-64^6)$

How can this possibly be correct!? Do what I said in post #8. Show all your working - every single step, starting with what is a and what is b.
• Dec 8th 2009, 12:20 PM
Mukilab
3v^3-192

^^^
original

a= $3v^3$
b= $-192$

$a^3=3v^3x^3=^9$, final answer is $3v^9 = a^3$
$b^3=-192^3$

http://www.mathhelpforum.com/math-he...a6b5924a-1.gif

$3v^9-192^3=(3v^3-192)(3v^6+(3v^3x(-192))-192^2)$
• Dec 8th 2009, 12:22 PM
Mukilab
Sorry for the x's, I do not know how to input multiplication
• Dec 8th 2009, 12:32 PM
manhmanh17vn
Quote:

Originally Posted by Mukilab
Finally?

http://www.mathhelpforum.com/math-he...c0888190-1.gif $\Rightarrow 3v^3-192$

http://www.mathhelpforum.com/math-he...a6b5924a-1.gif

$3v^9-64^9 \Rightarrow = (3v^3-64^3)(3v^6+3v^3(-64^3)-64^6)$

Quote:

Originally Posted by Mukilab
Sorry for the x's, I do not know how to input multiplication

Quote:

Originally Posted by Mukilab
3v^3-192

^^^
original

a= $3v^3$
b= $-192$

$a^3=3v^3x^3=^9$, final answer is $3v^9 = a^3$
$b^3=-192^3$

http://www.mathhelpforum.com/math-he...a6b5924a-1.gif

$3v^9-192^3=(3v^3-192)(3v^6+(3v^3x(-192))-192^2)$

firstt this you the the number 192 you can you use calculator to see $192=3*4^3$
and change this into the $3v^3-192$so you have $3v^3- 3*4^3$ $\Longrightarrow 3(v^3-4^3)$
so $a=v, b=4$