Question 614323


{{{-36m^2+6m+12}}} Start with the given expression.



{{{-6(6m^2-m-2)}}} Factor out the GCF {{{-6}}}.



Now let's try to factor the inner expression {{{6m^2-m-2}}}



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Looking at the expression {{{6m^2-m-2}}}, we can see that the first coefficient is {{{6}}}, the second coefficient is {{{-1}}}, and the last term is {{{-2}}}.



Now multiply the first coefficient {{{6}}} by the last term {{{-2}}} to get {{{(6)(-2)=-12}}}.



Now the question is: what two whole numbers multiply to {{{-12}}} (the previous product) <font size=4><b>and</b></font> add to the second coefficient {{{-1}}}?



To find these two numbers, we need to list <font size=4><b>all</b></font> of the factors of {{{-12}}} (the previous product).



Factors of {{{-12}}}:

1,2,3,4,6,12

-1,-2,-3,-4,-6,-12



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



These factors pair up and multiply to {{{-12}}}.

1*(-12) = -12
2*(-6) = -12
3*(-4) = -12
(-1)*(12) = -12
(-2)*(6) = -12
(-3)*(4) = -12


Now let's add up each pair of factors to see if one pair adds to the middle coefficient {{{-1}}}:



<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>-12</font></td><td  align="center"><font color=black>1+(-12)=-11</font></td></tr><tr><td  align="center"><font color=black>2</font></td><td  align="center"><font color=black>-6</font></td><td  align="center"><font color=black>2+(-6)=-4</font></td></tr><tr><td  align="center"><font color=red>3</font></td><td  align="center"><font color=red>-4</font></td><td  align="center"><font color=red>3+(-4)=-1</font></td></tr><tr><td  align="center"><font color=black>-1</font></td><td  align="center"><font color=black>12</font></td><td  align="center"><font color=black>-1+12=11</font></td></tr><tr><td  align="center"><font color=black>-2</font></td><td  align="center"><font color=black>6</font></td><td  align="center"><font color=black>-2+6=4</font></td></tr><tr><td  align="center"><font color=black>-3</font></td><td  align="center"><font color=black>4</font></td><td  align="center"><font color=black>-3+4=1</font></td></tr></table>



From the table, we can see that the two numbers {{{3}}} and {{{-4}}} add to {{{-1}}} (the middle coefficient).



So the two numbers {{{3}}} and {{{-4}}} both multiply to {{{-12}}} <font size=4><b>and</b></font> add to {{{-1}}}



Now replace the middle term {{{-1m}}} with {{{3m-4m}}}. Remember, {{{3}}} and {{{-4}}} add to {{{-1}}}. So this shows us that {{{3m-4m=-1m}}}.



{{{6m^2+highlight(3m-4m)-2}}} Replace the second term {{{-1m}}} with {{{3m-4m}}}.



{{{(6m^2+3m)+(-4m-2)}}} Group the terms into two pairs.



{{{3m(2m+1)+(-4m-2)}}} Factor out the GCF {{{3m}}} from the first group.



{{{3m(2m+1)-2(2m+1)}}} Factor out {{{2}}} 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.



{{{(3m-2)(2m+1)}}} Combine like terms. Or factor out the common term {{{2m+1}}}



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So {{{-6(6m^2-m-2)}}} then factors further to {{{-6(3m-2)(2m+1)}}}



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Answer:



So {{{-36m^2+6m+12}}} completely factors to {{{-6(3m-2)(2m+1)}}}.



In other words, {{{-36m^2+6m+12=-6(3m-2)(2m+1)}}}.



Note: you can check the answer by expanding {{{-6(3m-2)(2m+1)}}} to get {{{-36m^2+6m+12}}} or by graphing the original expression and the answer (the two graphs should be identical).


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