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Will you please factor this problem completely:6x^2-2x-20

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valgal987 | Student, Grade 9 | eNotes Newbie

Posted April 30, 2009 at 7:46 AM via web

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Will you please factor this problem completely:

6x^2-2x-20

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cburr | Middle School Teacher | (Level 2) Associate Educator

Posted April 30, 2009 at 10:28 AM (Answer #1)

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jovona's answer doesn't work.

Try this:

First, pull out 2:

2(3x^2 - x - 10)

Then factor the parenthetical:

2 (3x + 5)(x - 2)

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jovona | (Level 1) Salutatorian

Posted April 30, 2009 at 7:51 AM (Answer #2)

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6x^2-2x-20 =

3(2x^2-x-10) =

3(2x-5)(x+2)

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Wiggin42 | Student, Grade 11 | (Level 2) Valedictorian

Posted May 28, 2014 at 8:25 PM (Answer #3)

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6x^2-2x-20

Pull out the two : 

2 (3x^2 - x - 10)

We can factor the binomial and we know we'll end up with this: 

(3x + __ ) (x + __ ) 

The blanks are going to be filled with two numbers that multiply to give 10. Also, think about how when you foil this thing out, you have to end up with a -1 in the middle. Through reasoning we get: 

2 (3x + 5) (x - 2) 

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atyourservice | Student, Grade 10 | (Level 3) Valedictorian

Posted June 26, 2014 at 5:25 AM (Answer #4)

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6x^2-2x-20

factor out a 2

2 ( 3x^2 - x - 10)
      a        b     c
 
multiply a by c   3 x -10 = -30
 
find factors of -30 that subtract to b (-1)  which would be -6 and 5
 
plug those numbers in as b
 
3x^2 - 6x + 5x - 10
 
group
 
(3x^2 - 6x) + (5x - 10)
 
factor out
 
3x (x - 2 ) + 5 ( x -2)
 
put the numbers outside of the parentheses together:
 
(3x + 5) (x - 2)
 
include the 2 we first factored out
 
2 (3x + 5) (x - 2)  and that's the answer.

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