Question 549824


Looking at the expression {{{x^2+36x+308}}}, we can see that the first coefficient is {{{1}}}, the second coefficient is {{{36}}}, and the last term is {{{308}}}.



Now multiply the first coefficient {{{1}}} by the last term {{{308}}} to get {{{(1)(308)=308}}}.



Now the question is: what two whole numbers multiply to {{{308}}} (the previous product) <font size=4><b>and</b></font> add to the second coefficient {{{36}}}?



To find these two numbers, we need to list <font size=4><b>all</b></font> of the factors of {{{308}}} (the previous product).



Factors of {{{308}}}:

1,2,4,7,11,14,22,28,44,77,154,308

-1,-2,-4,-7,-11,-14,-22,-28,-44,-77,-154,-308



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



These factors pair up and multiply to {{{308}}}.

1*308 = 308
2*154 = 308
4*77 = 308
7*44 = 308
11*28 = 308
14*22 = 308
(-1)*(-308) = 308
(-2)*(-154) = 308
(-4)*(-77) = 308
(-7)*(-44) = 308
(-11)*(-28) = 308
(-14)*(-22) = 308


Now let's add up each pair of factors to see if one pair adds to the middle coefficient {{{36}}}:



<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>308</font></td><td  align="center"><font color=black>1+308=309</font></td></tr><tr><td  align="center"><font color=black>2</font></td><td  align="center"><font color=black>154</font></td><td  align="center"><font color=black>2+154=156</font></td></tr><tr><td  align="center"><font color=black>4</font></td><td  align="center"><font color=black>77</font></td><td  align="center"><font color=black>4+77=81</font></td></tr><tr><td  align="center"><font color=black>7</font></td><td  align="center"><font color=black>44</font></td><td  align="center"><font color=black>7+44=51</font></td></tr><tr><td  align="center"><font color=black>11</font></td><td  align="center"><font color=black>28</font></td><td  align="center"><font color=black>11+28=39</font></td></tr><tr><td  align="center"><font color=red>14</font></td><td  align="center"><font color=red>22</font></td><td  align="center"><font color=red>14+22=36</font></td></tr><tr><td  align="center"><font color=black>-1</font></td><td  align="center"><font color=black>-308</font></td><td  align="center"><font color=black>-1+(-308)=-309</font></td></tr><tr><td  align="center"><font color=black>-2</font></td><td  align="center"><font color=black>-154</font></td><td  align="center"><font color=black>-2+(-154)=-156</font></td></tr><tr><td  align="center"><font color=black>-4</font></td><td  align="center"><font color=black>-77</font></td><td  align="center"><font color=black>-4+(-77)=-81</font></td></tr><tr><td  align="center"><font color=black>-7</font></td><td  align="center"><font color=black>-44</font></td><td  align="center"><font color=black>-7+(-44)=-51</font></td></tr><tr><td  align="center"><font color=black>-11</font></td><td  align="center"><font color=black>-28</font></td><td  align="center"><font color=black>-11+(-28)=-39</font></td></tr><tr><td  align="center"><font color=black>-14</font></td><td  align="center"><font color=black>-22</font></td><td  align="center"><font color=black>-14+(-22)=-36</font></td></tr></table>



From the table, we can see that the two numbers {{{14}}} and {{{22}}} add to {{{36}}} (the middle coefficient).



So the two numbers {{{14}}} and {{{22}}} both multiply to {{{308}}} <font size=4><b>and</b></font> add to {{{36}}}



Now replace the middle term {{{36x}}} with {{{14x+22x}}}. Remember, {{{14}}} and {{{22}}} add to {{{36}}}. So this shows us that {{{14x+22x=36x}}}.



{{{x^2+highlight(14x+22x)+308}}} Replace the second term {{{36x}}} with {{{14x+22x}}}.



{{{(x^2+14x)+(22x+308)}}} Group the terms into two pairs.



{{{x(x+14)+(22x+308)}}} Factor out the GCF {{{x}}} from the first group.



{{{x(x+14)+22(x+14)}}} Factor out {{{22}}} 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+22)(x+14)}}} Combine like terms. Or factor out the common term {{{x+14}}}



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Answer:



So {{{x^2+36x+308}}} factors to {{{(x+22)(x+14)}}}.



In other words, {{{x^2+36x+308=(x+22)(x+14)}}}.



Note: you can check the answer by expanding {{{(x+22)(x+14)}}} to get {{{x^2+36x+308}}} or by graphing the original expression and the answer (the two graphs should be identical).