Question 522895


{{{6s^2+40s-64}}} Start with the given expression.



{{{2(3s^2+20s-32)}}} Factor out the GCF {{{2}}}.



Now let's try to factor the inner expression {{{3s^2+20s-32}}}



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Looking at the expression {{{3s^2+20s-32}}}, we can see that the first coefficient is {{{3}}}, the second coefficient is {{{20}}}, and the last term is {{{-32}}}.



Now multiply the first coefficient {{{3}}} by the last term {{{-32}}} to get {{{(3)(-32)=-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 {{{20}}}?



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 {{{20}}}:



<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=red>-4</font></td><td  align="center"><font color=red>24</font></td><td  align="center"><font color=red>-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 the two numbers {{{-4}}} and {{{24}}} add to {{{20}}} (the middle coefficient).



So the two numbers {{{-4}}} and {{{24}}} both multiply to {{{-96}}} <font size=4><b>and</b></font> add to {{{20}}}



Now replace the middle term {{{20s}}} with {{{-4s+24s}}}. Remember, {{{-4}}} and {{{24}}} add to {{{20}}}. So this shows us that {{{-4s+24s=20s}}}.



{{{3s^2+highlight(-4s+24s)-32}}} Replace the second term {{{20s}}} with {{{-4s+24s}}}.



{{{(3s^2-4s)+(24s-32)}}} Group the terms into two pairs.



{{{s(3s-4)+(24s-32)}}} Factor out the GCF {{{s}}} from the first group.



{{{s(3s-4)+8(3s-4)}}} 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.



{{{(s+8)(3s-4)}}} Combine like terms. Or factor out the common term {{{3s-4}}}



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So {{{2(3s^2+20s-32)}}} then factors further to {{{2(s+8)(3s-4)}}}



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Answer:



So {{{6s^2+40s-64}}} completely factors to {{{2(s+8)(3s-4)}}}.



In other words, {{{6s^2+40s-64=2(s+8)(3s-4)}}}.



Note: you can check the answer by expanding {{{2(s+8)(3s-4)}}} to get {{{6s^2+40s-64}}} or by graphing the original expression and the answer (the two graphs should be identical).



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