Question 355019


Looking at the expression {{{w^2+5w-14}}}, we can see that the first coefficient is {{{1}}}, the second coefficient is {{{5}}}, and the last term is {{{-14}}}.



Now multiply the first coefficient {{{1}}} by the last term {{{-14}}} to get {{{(1)(-14)=-14}}}.



Now the question is: what two whole numbers multiply to {{{-14}}} (the previous product) <font size=4><b>and</b></font> add to the second coefficient {{{5}}}?



To find these two numbers, we need to list <font size=4><b>all</b></font> of the factors of {{{-14}}} (the previous product).



Factors of {{{-14}}}:

1,2,7,14

-1,-2,-7,-14



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



These factors pair up and multiply to {{{-14}}}.

1*(-14) = -14
2*(-7) = -14
(-1)*(14) = -14
(-2)*(7) = -14


Now let's add up each pair of factors to see if one pair adds to the middle coefficient {{{5}}}:



<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>-14</font></td><td  align="center"><font color=black>1+(-14)=-13</font></td></tr><tr><td  align="center"><font color=black>2</font></td><td  align="center"><font color=black>-7</font></td><td  align="center"><font color=black>2+(-7)=-5</font></td></tr><tr><td  align="center"><font color=black>-1</font></td><td  align="center"><font color=black>14</font></td><td  align="center"><font color=black>-1+14=13</font></td></tr><tr><td  align="center"><font color=red>-2</font></td><td  align="center"><font color=red>7</font></td><td  align="center"><font color=red>-2+7=5</font></td></tr></table>



From the table, we can see that the two numbers {{{-2}}} and {{{7}}} add to {{{5}}} (the middle coefficient).



So the two numbers {{{-2}}} and {{{7}}} both multiply to {{{-14}}} <font size=4><b>and</b></font> add to {{{5}}}



Now replace the middle term {{{5w}}} with {{{-2w+7w}}}. Remember, {{{-2}}} and {{{7}}} add to {{{5}}}. So this shows us that {{{-2w+7w=5w}}}.



{{{w^2+highlight(-2w+7w)-14}}} Replace the second term {{{5w}}} with {{{-2w+7w}}}.



{{{(w^2-2w)+(7w-14)}}} Group the terms into two pairs.



{{{w(w-2)+(7w-14)}}} Factor out the GCF {{{w}}} from the first group.



{{{w(w-2)+7(w-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.



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



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Answer:



So {{{w^2+5w-14}}} factors to {{{(w+7)(w-2)}}}.



In other words, {{{w^2+5w-14=(w+7)(w-2)}}}.



Note: you can check the answer by expanding {{{(w+7)(w-2)}}} to get {{{w^2+5w-14}}} or by graphing the original expression and the answer (the two graphs should be identical).