Question 302560


{{{6x^5-11x^4+30x^3}}} Start with the given expression.



{{{x^3(6x^2-11x+30)}}} Factor out the GCF {{{x^3}}}.



Now let's try to factor the inner expression {{{6x^2-11x+30}}}



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Looking at the expression {{{6x^2-11x+30}}}, we can see that the first coefficient is {{{6}}}, the second coefficient is {{{-11}}}, and the last term is {{{30}}}.



Now multiply the first coefficient {{{6}}} by the last term {{{30}}} to get {{{(6)(30)=180}}}.



Now the question is: what two whole numbers multiply to {{{180}}} (the previous product) <font size=4><b>and</b></font> add to the second coefficient {{{-11}}}?



To find these two numbers, we need to list <font size=4><b>all</b></font> of the factors of {{{180}}} (the previous product).



Factors of {{{180}}}:

1,2,3,4,5,6,9,10,12,15,18,20,30,36,45,60,90,180

-1,-2,-3,-4,-5,-6,-9,-10,-12,-15,-18,-20,-30,-36,-45,-60,-90,-180



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



These factors pair up and multiply to {{{180}}}.

1*180 = 180
2*90 = 180
3*60 = 180
4*45 = 180
5*36 = 180
6*30 = 180
9*20 = 180
10*18 = 180
12*15 = 180
(-1)*(-180) = 180
(-2)*(-90) = 180
(-3)*(-60) = 180
(-4)*(-45) = 180
(-5)*(-36) = 180
(-6)*(-30) = 180
(-9)*(-20) = 180
(-10)*(-18) = 180
(-12)*(-15) = 180


Now let's add up each pair of factors to see if one pair adds to the middle coefficient {{{-11}}}:



<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>180</font></td><td  align="center"><font color=black>1+180=181</font></td></tr><tr><td  align="center"><font color=black>2</font></td><td  align="center"><font color=black>90</font></td><td  align="center"><font color=black>2+90=92</font></td></tr><tr><td  align="center"><font color=black>3</font></td><td  align="center"><font color=black>60</font></td><td  align="center"><font color=black>3+60=63</font></td></tr><tr><td  align="center"><font color=black>4</font></td><td  align="center"><font color=black>45</font></td><td  align="center"><font color=black>4+45=49</font></td></tr><tr><td  align="center"><font color=black>5</font></td><td  align="center"><font color=black>36</font></td><td  align="center"><font color=black>5+36=41</font></td></tr><tr><td  align="center"><font color=black>6</font></td><td  align="center"><font color=black>30</font></td><td  align="center"><font color=black>6+30=36</font></td></tr><tr><td  align="center"><font color=black>9</font></td><td  align="center"><font color=black>20</font></td><td  align="center"><font color=black>9+20=29</font></td></tr><tr><td  align="center"><font color=black>10</font></td><td  align="center"><font color=black>18</font></td><td  align="center"><font color=black>10+18=28</font></td></tr><tr><td  align="center"><font color=black>12</font></td><td  align="center"><font color=black>15</font></td><td  align="center"><font color=black>12+15=27</font></td></tr><tr><td  align="center"><font color=black>-1</font></td><td  align="center"><font color=black>-180</font></td><td  align="center"><font color=black>-1+(-180)=-181</font></td></tr><tr><td  align="center"><font color=black>-2</font></td><td  align="center"><font color=black>-90</font></td><td  align="center"><font color=black>-2+(-90)=-92</font></td></tr><tr><td  align="center"><font color=black>-3</font></td><td  align="center"><font color=black>-60</font></td><td  align="center"><font color=black>-3+(-60)=-63</font></td></tr><tr><td  align="center"><font color=black>-4</font></td><td  align="center"><font color=black>-45</font></td><td  align="center"><font color=black>-4+(-45)=-49</font></td></tr><tr><td  align="center"><font color=black>-5</font></td><td  align="center"><font color=black>-36</font></td><td  align="center"><font color=black>-5+(-36)=-41</font></td></tr><tr><td  align="center"><font color=black>-6</font></td><td  align="center"><font color=black>-30</font></td><td  align="center"><font color=black>-6+(-30)=-36</font></td></tr><tr><td  align="center"><font color=black>-9</font></td><td  align="center"><font color=black>-20</font></td><td  align="center"><font color=black>-9+(-20)=-29</font></td></tr><tr><td  align="center"><font color=black>-10</font></td><td  align="center"><font color=black>-18</font></td><td  align="center"><font color=black>-10+(-18)=-28</font></td></tr><tr><td  align="center"><font color=black>-12</font></td><td  align="center"><font color=black>-15</font></td><td  align="center"><font color=black>-12+(-15)=-27</font></td></tr></table>



From the table, we can see that there are no pairs of numbers which add to {{{-11}}}. So {{{6x^2-11x+30}}} cannot be factored.



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<a name="ans">


Answer:



So {{{6x^5-11x^4+30x^3}}} simply factors to {{{x^3(6x^2-11x+30)}}}



In other words, {{{6x^5-11x^4+30x^3=x^3(6x^2-11x+30)}}}.