Question 714312


Looking at the expression {{{x^2+2x-48}}}, we can see that the first coefficient is {{{1}}}, the second coefficient is {{{2}}}, and the last term is {{{-48}}}.



Now multiply the first coefficient {{{1}}} by the last term {{{-48}}} to get {{{(1)(-48)=-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 {{{2}}}?



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 {{{2}}}:



<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=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><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=red>-6</font></td><td  align="center"><font color=red>8</font></td><td  align="center"><font color=red>-6+8=2</font></td></tr></table>



From the table, we can see that the two numbers {{{-6}}} and {{{8}}} add to {{{2}}} (the middle coefficient).



So the two numbers {{{-6}}} and {{{8}}} both multiply to {{{-48}}} <font size=4><b>and</b></font> add to {{{2}}}



Now replace the middle term {{{2x}}} with {{{-6x+8x}}}. Remember, {{{-6}}} and {{{8}}} add to {{{2}}}. So this shows us that {{{-6x+8x=2x}}}.



{{{x^2+highlight(-6x+8x)-48}}} Replace the second term {{{2x}}} with {{{-6x+8x}}}.



{{{(x^2-6x)+(8x-48)}}} Group the terms into two pairs.



{{{x(x-6)+(8x-48)}}} Factor out the GCF {{{x}}} from the first group.



{{{x(x-6)+8(x-6)}}} Factor out {{{8}}} 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.



{{{(x+8)(x-6)}}} Combine like terms. Or factor out the common term {{{x-6}}}



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Answer:



So {{{x^2+2x-48}}} factors to {{{(x+8)(x-6)}}}.



In other words, {{{x^2+2x-48=(x+8)(x-6)}}}.



Note: you can check the answer by expanding {{{(x+8)(x-6)}}} to get {{{x^2+2x-48}}} or by graphing the original expression and the answer (the two graphs should be identical).