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# factoring expressions?

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1) 6x^2 + 2xy - 15x - 5y

2) 2x^2 + 7x + 5

Guest Jul 19, 2017
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#1
+76821
+2

1) 6x^2 + 2xy - 15x - 5y

factor by grouping

2x (3x + y ) - 5 (3x + y)        (3x + y)   is common to both terms

(3x + y)   (2x - 5 )

2) 2x^2 + 7x + 5    we're looking for two terms that multiply to 2 for the first term and to 5 for the last term......trial and error produces

(2x + 5) (x + 1)

CPhill  Jul 19, 2017
#2
0

wait, how did you get your last answer for question 2? :)

Guest Jul 19, 2017
#3
+4694
+1

Here's another way to do that one....

2x2 + 7x + 5

Multiply the  2  and the  5  together to get  10  .

What two numbers multiply to  10  and add to  7  ? →   +2   and   +5

So, we can split the middle term like this:

2x2 + 2x + 5x + 5              Notice here how if we combined like terms, we'd get  7x  again.

Factor  2x  out of the first two terms.

2x(x + 1) + 5x + 5

Factor  5  out of the last two terms.

2x(x + 1) + 5(x + 1)

Factor  (x + 1)  out of both remaining terms.

(x + 1)(2x + 5)

hectictar  Jul 19, 2017

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