Question 387234


{{{27x^2y+180xy^2+75y^3}}} Start with the given expression.



{{{3y(9x^2+60xy+25y^2)}}} Factor out the GCF {{{3y}}}.



Now let's try to factor the inner expression {{{9x^2+60xy+25y^2}}}



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Looking at the expression {{{9x^2+60xy+25y^2}}}, we can see that the first coefficient is {{{9}}}, the second coefficient is {{{60}}}, and the last coefficient is {{{25}}}.



Now multiply the first coefficient {{{9}}} by the last coefficient {{{25}}} to get {{{(9)(25)=225}}}.



Now the question is: what two whole numbers multiply to {{{225}}} (the previous product) <font size=4><b>and</b></font> add to the second coefficient {{{60}}}?



To find these two numbers, we need to list <font size=4><b>all</b></font> of the factors of {{{225}}} (the previous product).



Factors of {{{225}}}:

1,3,5,9,15,25,45,75,225

-1,-3,-5,-9,-15,-25,-45,-75,-225



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



These factors pair up and multiply to {{{225}}}.

1*225 = 225
3*75 = 225
5*45 = 225
9*25 = 225
15*15 = 225
(-1)*(-225) = 225
(-3)*(-75) = 225
(-5)*(-45) = 225
(-9)*(-25) = 225
(-15)*(-15) = 225


Now let's add up each pair of factors to see if one pair adds to the middle coefficient {{{60}}}:



<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>225</font></td><td  align="center"><font color=black>1+225=226</font></td></tr><tr><td  align="center"><font color=black>3</font></td><td  align="center"><font color=black>75</font></td><td  align="center"><font color=black>3+75=78</font></td></tr><tr><td  align="center"><font color=black>5</font></td><td  align="center"><font color=black>45</font></td><td  align="center"><font color=black>5+45=50</font></td></tr><tr><td  align="center"><font color=black>9</font></td><td  align="center"><font color=black>25</font></td><td  align="center"><font color=black>9+25=34</font></td></tr><tr><td  align="center"><font color=black>15</font></td><td  align="center"><font color=black>15</font></td><td  align="center"><font color=black>15+15=30</font></td></tr><tr><td  align="center"><font color=black>-1</font></td><td  align="center"><font color=black>-225</font></td><td  align="center"><font color=black>-1+(-225)=-226</font></td></tr><tr><td  align="center"><font color=black>-3</font></td><td  align="center"><font color=black>-75</font></td><td  align="center"><font color=black>-3+(-75)=-78</font></td></tr><tr><td  align="center"><font color=black>-5</font></td><td  align="center"><font color=black>-45</font></td><td  align="center"><font color=black>-5+(-45)=-50</font></td></tr><tr><td  align="center"><font color=black>-9</font></td><td  align="center"><font color=black>-25</font></td><td  align="center"><font color=black>-9+(-25)=-34</font></td></tr><tr><td  align="center"><font color=black>-15</font></td><td  align="center"><font color=black>-15</font></td><td  align="center"><font color=black>-15+(-15)=-30</font></td></tr></table>



From the table, we can see that there are no pairs of numbers which add to {{{60}}}. So {{{9x^2+60xy+25y^2}}} cannot be factored.



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<a name="ans">


Answer:



So {{{27x^2y+180xy^2+75y^3}}} simply factors to {{{3y(9x^2+60xy+25y^2)}}}



In other words, {{{27x^2y+180xy^2+75y^3=3y(9x^2+60xy+25y^2)}}}.



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Jim