Question 760562


Looking at the expression {{{12h^2-13hj-4j^2}}}, we can see that the first coefficient is {{{12}}}, the second coefficient is {{{-13}}}, and the last coefficient is {{{-4}}}.



Now multiply the first coefficient {{{12}}} by the last coefficient {{{-4}}} to get {{{(12)(-4)=-48}}}.



Now the question is: what two whole numbers multiply to {{{-48}}} (the previous product) <font size=4><b>and</b></font> add to the second coefficient {{{-13}}}?



To find these two numbers, we need to list <font size=4><b>all</b></font> of the factors of {{{-48}}} (the previous product).



Factors of {{{-48}}}:

1,2,3,4,6,8,12,16,24,48

-1,-2,-3,-4,-6,-8,-12,-16,-24,-48



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



These factors pair up and multiply to {{{-48}}}.

1*(-48) = -48
2*(-24) = -48
3*(-16) = -48
4*(-12) = -48
6*(-8) = -48
(-1)*(48) = -48
(-2)*(24) = -48
(-3)*(16) = -48
(-4)*(12) = -48
(-6)*(8) = -48


Now let's add up each pair of factors to see if one pair adds to the middle coefficient {{{-13}}}:



<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>-48</font></td><td  align="center"><font color=black>1+(-48)=-47</font></td></tr><tr><td  align="center"><font color=black>2</font></td><td  align="center"><font color=black>-24</font></td><td  align="center"><font color=black>2+(-24)=-22</font></td></tr><tr><td  align="center"><font color=red>3</font></td><td  align="center"><font color=red>-16</font></td><td  align="center"><font color=red>3+(-16)=-13</font></td></tr><tr><td  align="center"><font color=black>4</font></td><td  align="center"><font color=black>-12</font></td><td  align="center"><font color=black>4+(-12)=-8</font></td></tr><tr><td  align="center"><font color=black>6</font></td><td  align="center"><font color=black>-8</font></td><td  align="center"><font color=black>6+(-8)=-2</font></td></tr><tr><td  align="center"><font color=black>-1</font></td><td  align="center"><font color=black>48</font></td><td  align="center"><font color=black>-1+48=47</font></td></tr><tr><td  align="center"><font color=black>-2</font></td><td  align="center"><font color=black>24</font></td><td  align="center"><font color=black>-2+24=22</font></td></tr><tr><td  align="center"><font color=black>-3</font></td><td  align="center"><font color=black>16</font></td><td  align="center"><font color=black>-3+16=13</font></td></tr><tr><td  align="center"><font color=black>-4</font></td><td  align="center"><font color=black>12</font></td><td  align="center"><font color=black>-4+12=8</font></td></tr><tr><td  align="center"><font color=black>-6</font></td><td  align="center"><font color=black>8</font></td><td  align="center"><font color=black>-6+8=2</font></td></tr></table>



From the table, we can see that the two numbers {{{3}}} and {{{-16}}} add to {{{-13}}} (the middle coefficient).



So the two numbers {{{3}}} and {{{-16}}} both multiply to {{{-48}}} <font size=4><b>and</b></font> add to {{{-13}}}



Now replace the middle term {{{-13hj}}} with {{{3hj-16hj}}}. Remember, {{{3}}} and {{{-16}}} add to {{{-13}}}. So this shows us that {{{3hj-16hj=-13hj}}}.



{{{12h^2+highlight(3hj-16hj)-4j^2}}} Replace the second term {{{-13hj}}} with {{{3hj-16hj}}}.



{{{(12h^2+3hj)+(-16hj-4j^2)}}} Group the terms into two pairs.



{{{3h(4h+j)+(-16hj-4j^2)}}} Factor out the GCF {{{3h}}} from the first group.


{{{3h(4h+j)-4j(4h+j)}}} Factor out {{{-4j}}} from the second group.


{{{(3h-4j)(4h+j)}}} Factor out the GCF {{{4h+j}}} from the entire expression


Final Answer: {{{(3h-4j)(4h+j)}}}