Hello,

I need to factor out

x^2 - 7x +12
= 0

and this is what I did...
I factored out the -7x
⇒ x^2 - 4x - 3x +12 = 0
Then I grouped them

⇒ (x^2 - 4x) - (3x +12) = 0
⇒ x (x - 4) - (????) = 0

That's where I'm lost
I can't seem to be able to factor out -(3x+12) into having a factor of (x-4)
it always comes out as -3(x+4)

I hope someone can help. :)

2

Answers

The Brainliest Answer!
2014-07-22T13:18:57+08:00

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It should be -3(x-4) because the negative sign will also be distributed so it will be equal to -3x+12 which is what is in the original equation.

You made a mistake in grouping the terms here: 
(x² - 4x) - (3x +12) = 0

You should've included the negative sign for 3x: 
(x² - 4x) + (-3x +12) = 0
or changed +12 to -12 since you initially factored out the - sign: 
(x² - 4x) - (3x -12) = 0

Any of these two would've given you the right answer :)

If you used -3(x+4), that will be equal to -3x -12, which is not similar to the equation.


Btw, i like how you factor :) It's different from how a typical high school student does it
2 5 2
How different? Hahaha I thought it was like a normal way. Anyway thanks!
Shall I explain more? Well, a lot would just think of two factors that would satisfy the equation, without doing grouping and factoring out, like what you did. :D
so it's like the others have no process or anything?
or does mine come out a bit immature?
No not immature. I find this method easier and more systematic, although to use it one needs to understand the concept behind the method. I think you really understand how math works, if you know what i mean.
2014-07-22T19:13:25+08:00

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Answer: (X - 3)(X - 4)


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