Question 243599


Looking at the expression {{{10m^2-17m+3}}}, we can see that the first coefficient is {{{10}}}, the second coefficient is {{{-17}}}, and the last term is {{{3}}}.



Now multiply the first coefficient {{{10}}} by the last term {{{3}}} to get {{{(10)(3)=30}}}.



Now the question is: what two whole numbers multiply to {{{30}}} (the previous product) <font size=4><b>and</b></font> add to the second coefficient {{{-17}}}?



To find these two numbers, we need to list <font size=4><b>all</b></font> of the factors of {{{30}}} (the previous product).



Factors of {{{30}}}:

1,2,3,5,6,10,15,30

-1,-2,-3,-5,-6,-10,-15,-30



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



These factors pair up and multiply to {{{30}}}.

1*30 = 30
2*15 = 30
3*10 = 30
5*6 = 30
(-1)*(-30) = 30
(-2)*(-15) = 30
(-3)*(-10) = 30
(-5)*(-6) = 30


Now let's add up each pair of factors to see if one pair adds to the middle coefficient {{{-17}}}:



<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>30</font></td><td  align="center"><font color=black>1+30=31</font></td></tr><tr><td  align="center"><font color=black>2</font></td><td  align="center"><font color=black>15</font></td><td  align="center"><font color=black>2+15=17</font></td></tr><tr><td  align="center"><font color=black>3</font></td><td  align="center"><font color=black>10</font></td><td  align="center"><font color=black>3+10=13</font></td></tr><tr><td  align="center"><font color=black>5</font></td><td  align="center"><font color=black>6</font></td><td  align="center"><font color=black>5+6=11</font></td></tr><tr><td  align="center"><font color=black>-1</font></td><td  align="center"><font color=black>-30</font></td><td  align="center"><font color=black>-1+(-30)=-31</font></td></tr><tr><td  align="center"><font color=red>-2</font></td><td  align="center"><font color=red>-15</font></td><td  align="center"><font color=red>-2+(-15)=-17</font></td></tr><tr><td  align="center"><font color=black>-3</font></td><td  align="center"><font color=black>-10</font></td><td  align="center"><font color=black>-3+(-10)=-13</font></td></tr><tr><td  align="center"><font color=black>-5</font></td><td  align="center"><font color=black>-6</font></td><td  align="center"><font color=black>-5+(-6)=-11</font></td></tr></table>



From the table, we can see that the two numbers {{{-2}}} and {{{-15}}} add to {{{-17}}} (the middle coefficient).



So the two numbers {{{-2}}} and {{{-15}}} both multiply to {{{30}}} <font size=4><b>and</b></font> add to {{{-17}}}



Now replace the middle term {{{-17m}}} with {{{-2m-15m}}}. Remember, {{{-2}}} and {{{-15}}} add to {{{-17}}}. So this shows us that {{{-2m-15m=-17m}}}.



{{{10m^2+highlight(-2m-15m)+3}}} Replace the second term {{{-17m}}} with {{{-2m-15m}}}.



{{{(10m^2-2m)+(-15m+3)}}} Group the terms into two pairs.



{{{2m(5m-1)+(-15m+3)}}} Factor out the GCF {{{2m}}} from the first group.



{{{2m(5m-1)-3(5m-1)}}} Factor out {{{3}}} 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.



{{{(2m-3)(5m-1)}}} Combine like terms. Or factor out the common term {{{5m-1}}}



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Answer:



So {{{10m^2-17m+3}}} factors to {{{(2m-3)(5m-1)}}}.



In other words, {{{10m^2-17m+3=(2m-3)(5m-1)}}}.



Note: you can check the answer by expanding {{{(2m-3)(5m-1)}}} to get {{{10m^2-17m+3}}} or by graphing the original expression and the answer (the two graphs should be identical).