Question 704991


{{{24w^4-20w^3-16w^2}}} Start with the given expression.



{{{4w^2(6w^2-5w-4)}}} Factor out the GCF {{{4w^2}}}.



Now let's try to factor the inner expression {{{6w^2-5w-4}}}



---------------------------------------------------------------



Looking at the expression {{{6w^2-5w-4}}}, we can see that the first coefficient is {{{6}}}, the second coefficient is {{{-5}}}, and the last term is {{{-4}}}.



Now multiply the first coefficient {{{6}}} by the last term {{{-4}}} to get {{{(6)(-4)=-24}}}.



Now the question is: what two whole numbers multiply to {{{-24}}} (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 {{{-24}}} (the previous product).



Factors of {{{-24}}}:

1,2,3,4,6,8,12,24

-1,-2,-3,-4,-6,-8,-12,-24



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



These factors pair up and multiply to {{{-24}}}.

1*(-24) = -24
2*(-12) = -24
3*(-8) = -24
4*(-6) = -24
(-1)*(24) = -24
(-2)*(12) = -24
(-3)*(8) = -24
(-4)*(6) = -24


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>-24</font></td><td  align="center"><font color=black>1+(-24)=-23</font></td></tr><tr><td  align="center"><font color=black>2</font></td><td  align="center"><font color=black>-12</font></td><td  align="center"><font color=black>2+(-12)=-10</font></td></tr><tr><td  align="center"><font color=red>3</font></td><td  align="center"><font color=red>-8</font></td><td  align="center"><font color=red>3+(-8)=-5</font></td></tr><tr><td  align="center"><font color=black>4</font></td><td  align="center"><font color=black>-6</font></td><td  align="center"><font color=black>4+(-6)=-2</font></td></tr><tr><td  align="center"><font color=black>-1</font></td><td  align="center"><font color=black>24</font></td><td  align="center"><font color=black>-1+24=23</font></td></tr><tr><td  align="center"><font color=black>-2</font></td><td  align="center"><font color=black>12</font></td><td  align="center"><font color=black>-2+12=10</font></td></tr><tr><td  align="center"><font color=black>-3</font></td><td  align="center"><font color=black>8</font></td><td  align="center"><font color=black>-3+8=5</font></td></tr><tr><td  align="center"><font color=black>-4</font></td><td  align="center"><font color=black>6</font></td><td  align="center"><font color=black>-4+6=2</font></td></tr></table>



From the table, we can see that the two numbers {{{3}}} and {{{-8}}} add to {{{-5}}} (the middle coefficient).



So the two numbers {{{3}}} and {{{-8}}} both multiply to {{{-24}}} <font size=4><b>and</b></font> add to {{{-5}}}



Now replace the middle term {{{-5w}}} with {{{3w-8w}}}. Remember, {{{3}}} and {{{-8}}} add to {{{-5}}}. So this shows us that {{{3w-8w=-5w}}}.



{{{6w^2+highlight(3w-8w)-4}}} Replace the second term {{{-5w}}} with {{{3w-8w}}}.



{{{(6w^2+3w)+(-8w-4)}}} Group the terms into two pairs.



{{{3w(2w+1)+(-8w-4)}}} Factor out the GCF {{{3w}}} from the first group.



{{{3w(2w+1)-4(2w+1)}}} Factor out {{{4}}} 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.



{{{(3w-4)(2w+1)}}} Combine like terms. Or factor out the common term {{{2w+1}}}



--------------------------------------------------



So {{{4w^2(6w^2-5w-4)}}} then factors further to {{{4w^2(3w-4)(2w+1)}}}



===============================================================



Answer:



So {{{24w^4-20w^3-16w^2}}} completely factors to {{{4w^2(3w-4)(2w+1)}}}.



In other words, {{{24w^4-20w^3-16w^2=4w^2(3w-4)(2w+1)}}}.



Note: you can check the answer by expanding {{{4w^2(3w-4)(2w+1)}}} to get {{{24w^4-20w^3-16w^2}}} or by graphing the original expression and the answer (the two graphs should be identical).


<font color="red">--------------------------------------------------------------------------------------------------------------</font>


If you need more help, you can email me at <a href="mailto:jim_thompson5910@hotmail.com?Subject=I%20Need%20Algebra%20Help">jim_thompson5910@hotmail.com</a>


To find other ways to contact me, you can also visit my website: <a href="http://www.freewebs.com/jimthompson5910/home.html">http://www.freewebs.com/jimthompson5910/home.html</a>


Thanks,


Jim


<font color="red">--------------------------------------------------------------------------------------------------------------</font>