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

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cburr's profile pic

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

Posted on

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)

atyourservice's profile pic

atyourservice | Student, Grade 11 | (Level 3) Valedictorian

Posted on

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.
Wiggin42's profile pic

Wiggin42 | Student, Undergraduate | (Level 2) Valedictorian

Posted on

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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