Question 539461


{{{6y^3+25y^2+14y}}} Start with the given expression.



{{{y(6y^2+25y+14)}}} Factor out the GCF {{{y}}}.



Now let's try to factor the inner expression {{{6y^2+25y+14}}}



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Looking at the expression {{{6y^2+25y+14}}}, we can see that the first coefficient is {{{6}}}, the second coefficient is {{{25}}}, and the last term is {{{14}}}.



Now multiply the first coefficient {{{6}}} by the last term {{{14}}} to get {{{(6)(14)=84}}}.



Now the question is: what two whole numbers multiply to {{{84}}} (the previous product) <font size=4><b>and</b></font> add to the second coefficient {{{25}}}?



To find these two numbers, we need to list <font size=4><b>all</b></font> of the factors of {{{84}}} (the previous product).



Factors of {{{84}}}:

1,2,3,4,6,7,12,14,21,28,42,84

-1,-2,-3,-4,-6,-7,-12,-14,-21,-28,-42,-84



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



These factors pair up and multiply to {{{84}}}.

1*84 = 84
2*42 = 84
3*28 = 84
4*21 = 84
6*14 = 84
7*12 = 84
(-1)*(-84) = 84
(-2)*(-42) = 84
(-3)*(-28) = 84
(-4)*(-21) = 84
(-6)*(-14) = 84
(-7)*(-12) = 84


Now let's add up each pair of factors to see if one pair adds to the middle coefficient {{{25}}}:



<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>84</font></td><td  align="center"><font color=black>1+84=85</font></td></tr><tr><td  align="center"><font color=black>2</font></td><td  align="center"><font color=black>42</font></td><td  align="center"><font color=black>2+42=44</font></td></tr><tr><td  align="center"><font color=black>3</font></td><td  align="center"><font color=black>28</font></td><td  align="center"><font color=black>3+28=31</font></td></tr><tr><td  align="center"><font color=red>4</font></td><td  align="center"><font color=red>21</font></td><td  align="center"><font color=red>4+21=25</font></td></tr><tr><td  align="center"><font color=black>6</font></td><td  align="center"><font color=black>14</font></td><td  align="center"><font color=black>6+14=20</font></td></tr><tr><td  align="center"><font color=black>7</font></td><td  align="center"><font color=black>12</font></td><td  align="center"><font color=black>7+12=19</font></td></tr><tr><td  align="center"><font color=black>-1</font></td><td  align="center"><font color=black>-84</font></td><td  align="center"><font color=black>-1+(-84)=-85</font></td></tr><tr><td  align="center"><font color=black>-2</font></td><td  align="center"><font color=black>-42</font></td><td  align="center"><font color=black>-2+(-42)=-44</font></td></tr><tr><td  align="center"><font color=black>-3</font></td><td  align="center"><font color=black>-28</font></td><td  align="center"><font color=black>-3+(-28)=-31</font></td></tr><tr><td  align="center"><font color=black>-4</font></td><td  align="center"><font color=black>-21</font></td><td  align="center"><font color=black>-4+(-21)=-25</font></td></tr><tr><td  align="center"><font color=black>-6</font></td><td  align="center"><font color=black>-14</font></td><td  align="center"><font color=black>-6+(-14)=-20</font></td></tr><tr><td  align="center"><font color=black>-7</font></td><td  align="center"><font color=black>-12</font></td><td  align="center"><font color=black>-7+(-12)=-19</font></td></tr></table>



From the table, we can see that the two numbers {{{4}}} and {{{21}}} add to {{{25}}} (the middle coefficient).



So the two numbers {{{4}}} and {{{21}}} both multiply to {{{84}}} <font size=4><b>and</b></font> add to {{{25}}}



Now replace the middle term {{{25y}}} with {{{4y+21y}}}. Remember, {{{4}}} and {{{21}}} add to {{{25}}}. So this shows us that {{{4y+21y=25y}}}.



{{{6y^2+highlight(4y+21y)+14}}} Replace the second term {{{25y}}} with {{{4y+21y}}}.



{{{(6y^2+4y)+(21y+14)}}} Group the terms into two pairs.



{{{2y(3y+2)+(21y+14)}}} Factor out the GCF {{{2y}}} from the first group.



{{{2y(3y+2)+7(3y+2)}}} Factor out {{{7}}} from the second group. The goal of this step is to make the terms in the second parenthesis equal to the terms in the first parenthesis.



{{{(2y+7)(3y+2)}}} Combine like terms. Or factor out the common term {{{3y+2}}}



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So {{{y(6y^2+25y+14)}}} then factors further to {{{y(2y+7)(3y+2)}}}



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Answer:



So {{{6y^3+25y^2+14y}}} completely factors to {{{y(2y+7)(3y+2)}}}.



In other words, {{{6y^3+25y^2+14y=y(2y+7)(3y+2)}}}.



Note: you can check the answer by expanding {{{y(2y+7)(3y+2)}}} to get {{{6y^3+25y^2+14y}}} or by graphing the original expression and the answer (the two graphs should be identical).



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