Question 540467


Looking at the expression {{{m^2+30m-96}}}, we can see that the first coefficient is {{{1}}}, the second coefficient is {{{30}}}, and the last term is {{{-96}}}.



Now multiply the first coefficient {{{1}}} by the last term {{{-96}}} to get {{{(1)(-96)=-96}}}.



Now the question is: what two whole numbers multiply to {{{-96}}} (the previous product) <font size=4><b>and</b></font> add to the second coefficient {{{30}}}?



To find these two numbers, we need to list <font size=4><b>all</b></font> of the factors of {{{-96}}} (the previous product).



Factors of {{{-96}}}:

1,2,3,4,6,8,12,16,24,32,48,96

-1,-2,-3,-4,-6,-8,-12,-16,-24,-32,-48,-96



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



These factors pair up and multiply to {{{-96}}}.

1*(-96) = -96
2*(-48) = -96
3*(-32) = -96
4*(-24) = -96
6*(-16) = -96
8*(-12) = -96
(-1)*(96) = -96
(-2)*(48) = -96
(-3)*(32) = -96
(-4)*(24) = -96
(-6)*(16) = -96
(-8)*(12) = -96


Now let's add up each pair of factors to see if one pair adds to the middle coefficient {{{30}}}:



<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>-96</font></td><td  align="center"><font color=black>1+(-96)=-95</font></td></tr><tr><td  align="center"><font color=black>2</font></td><td  align="center"><font color=black>-48</font></td><td  align="center"><font color=black>2+(-48)=-46</font></td></tr><tr><td  align="center"><font color=black>3</font></td><td  align="center"><font color=black>-32</font></td><td  align="center"><font color=black>3+(-32)=-29</font></td></tr><tr><td  align="center"><font color=black>4</font></td><td  align="center"><font color=black>-24</font></td><td  align="center"><font color=black>4+(-24)=-20</font></td></tr><tr><td  align="center"><font color=black>6</font></td><td  align="center"><font color=black>-16</font></td><td  align="center"><font color=black>6+(-16)=-10</font></td></tr><tr><td  align="center"><font color=black>8</font></td><td  align="center"><font color=black>-12</font></td><td  align="center"><font color=black>8+(-12)=-4</font></td></tr><tr><td  align="center"><font color=black>-1</font></td><td  align="center"><font color=black>96</font></td><td  align="center"><font color=black>-1+96=95</font></td></tr><tr><td  align="center"><font color=black>-2</font></td><td  align="center"><font color=black>48</font></td><td  align="center"><font color=black>-2+48=46</font></td></tr><tr><td  align="center"><font color=black>-3</font></td><td  align="center"><font color=black>32</font></td><td  align="center"><font color=black>-3+32=29</font></td></tr><tr><td  align="center"><font color=black>-4</font></td><td  align="center"><font color=black>24</font></td><td  align="center"><font color=black>-4+24=20</font></td></tr><tr><td  align="center"><font color=black>-6</font></td><td  align="center"><font color=black>16</font></td><td  align="center"><font color=black>-6+16=10</font></td></tr><tr><td  align="center"><font color=black>-8</font></td><td  align="center"><font color=black>12</font></td><td  align="center"><font color=black>-8+12=4</font></td></tr></table>



From the table, we can see that there are no pairs of numbers which add to {{{30}}}. So {{{m^2+30m-96}}} cannot be factored.



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<a name="ans">


Answer:



So {{{m^2+30m-96}}} doesn't factor at all (over the rational numbers).



So {{{m^2+30m-96}}} is prime.



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