Question 607737


{{{-12x^3y^5-9x^2y^2+12xy^3}}} Start with the given expression.



{{{-3xy^2(4x^2y^3+3x-4y)}}} Factor out the GCF {{{-3xy^2}}}.



Now let's try to factor the inner expression {{{4x^2y^3+3x-4y}}}



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Looking at the expression {{{4x^2y^3+3x-4y}}}, we can see that the first coefficient is {{{4}}}, the second coefficient is {{{3}}}, and the last coefficient is {{{-4}}}.



Now multiply the first coefficient {{{4}}} by the last coefficient {{{-4}}} to get {{{(4)(-4)=-16}}}.



Now the question is: what two whole numbers multiply to {{{-16}}} (the previous product) <font size=4><b>and</b></font> add to the second coefficient {{{3}}}?



To find these two numbers, we need to list <font size=4><b>all</b></font> of the factors of {{{-16}}} (the previous product).



Factors of {{{-16}}}:

1,2,4,8,16

-1,-2,-4,-8,-16



Note: list the negative of each factor. This will allow us to find all possible combinations.



These factors pair up and multiply to {{{-16}}}.

1*(-16) = -16
2*(-8) = -16
4*(-4) = -16
(-1)*(16) = -16
(-2)*(8) = -16
(-4)*(4) = -16


Now let's add up each pair of factors to see if one pair adds to the middle coefficient {{{3}}}:



<table border="1"><th>First Number</th><th>Second Number</th><th>Sum</th><tr><td  align="center"><font color=black>1</font></td><td  align="center"><font color=black>-16</font></td><td  align="center"><font color=black>1+(-16)=-15</font></td></tr><tr><td  align="center"><font color=black>2</font></td><td  align="center"><font color=black>-8</font></td><td  align="center"><font color=black>2+(-8)=-6</font></td></tr><tr><td  align="center"><font color=black>4</font></td><td  align="center"><font color=black>-4</font></td><td  align="center"><font color=black>4+(-4)=0</font></td></tr><tr><td  align="center"><font color=black>-1</font></td><td  align="center"><font color=black>16</font></td><td  align="center"><font color=black>-1+16=15</font></td></tr><tr><td  align="center"><font color=black>-2</font></td><td  align="center"><font color=black>8</font></td><td  align="center"><font color=black>-2+8=6</font></td></tr><tr><td  align="center"><font color=black>-4</font></td><td  align="center"><font color=black>4</font></td><td  align="center"><font color=black>-4+4=0</font></td></tr></table>



From the table, we can see that there are no pairs of numbers which add to {{{3}}}. So {{{4x^2y^3+3x-4y}}} cannot be factored.



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<a name="ans">


Answer:



So {{{-12x^3y^5-9x^2y^2+12xy^3}}} simply factors to {{{-3xy^2(4x^2y^3+3x-4y)}}}



In other words, {{{-12x^3y^5-9x^2y^2+12xy^3=-3xy^2(4x^2y^3+3x-4y)}}}.

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