Question 185528
I assume that you want to factor.




Looking at the expression {{{10x^2+23x+12}}}, we can see that the first coefficient is {{{10}}}, the second coefficient is {{{23}}}, and the last term is {{{12}}}.



Now multiply the first coefficient {{{10}}} by the last term {{{12}}} to get {{{(10)(12)=120}}}.



Now the question is: what two whole numbers multiply to {{{120}}} (the previous product) <font size=4><b>and</b></font> add to the second coefficient {{{23}}}?



To find these two numbers, we need to list <font size=4><b>all</b></font> of the factors of {{{120}}} (the previous product).



Factors of {{{120}}}:

1,2,3,4,5,6,8,10,12,15,20,24,30,40,60,120

-1,-2,-3,-4,-5,-6,-8,-10,-12,-15,-20,-24,-30,-40,-60,-120



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



These factors pair up and multiply to {{{120}}}.

1*120
2*60
3*40
4*30
5*24
6*20
8*15
10*12
(-1)*(-120)
(-2)*(-60)
(-3)*(-40)
(-4)*(-30)
(-5)*(-24)
(-6)*(-20)
(-8)*(-15)
(-10)*(-12)


Now let's add up each pair of factors to see if one pair adds to the middle coefficient {{{23}}}:



<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>120</font></td><td  align="center"><font color=black>1+120=121</font></td></tr><tr><td  align="center"><font color=black>2</font></td><td  align="center"><font color=black>60</font></td><td  align="center"><font color=black>2+60=62</font></td></tr><tr><td  align="center"><font color=black>3</font></td><td  align="center"><font color=black>40</font></td><td  align="center"><font color=black>3+40=43</font></td></tr><tr><td  align="center"><font color=black>4</font></td><td  align="center"><font color=black>30</font></td><td  align="center"><font color=black>4+30=34</font></td></tr><tr><td  align="center"><font color=black>5</font></td><td  align="center"><font color=black>24</font></td><td  align="center"><font color=black>5+24=29</font></td></tr><tr><td  align="center"><font color=black>6</font></td><td  align="center"><font color=black>20</font></td><td  align="center"><font color=black>6+20=26</font></td></tr><tr><td  align="center"><font color=red>8</font></td><td  align="center"><font color=red>15</font></td><td  align="center"><font color=red>8+15=23</font></td></tr><tr><td  align="center"><font color=black>10</font></td><td  align="center"><font color=black>12</font></td><td  align="center"><font color=black>10+12=22</font></td></tr><tr><td  align="center"><font color=black>-1</font></td><td  align="center"><font color=black>-120</font></td><td  align="center"><font color=black>-1+(-120)=-121</font></td></tr><tr><td  align="center"><font color=black>-2</font></td><td  align="center"><font color=black>-60</font></td><td  align="center"><font color=black>-2+(-60)=-62</font></td></tr><tr><td  align="center"><font color=black>-3</font></td><td  align="center"><font color=black>-40</font></td><td  align="center"><font color=black>-3+(-40)=-43</font></td></tr><tr><td  align="center"><font color=black>-4</font></td><td  align="center"><font color=black>-30</font></td><td  align="center"><font color=black>-4+(-30)=-34</font></td></tr><tr><td  align="center"><font color=black>-5</font></td><td  align="center"><font color=black>-24</font></td><td  align="center"><font color=black>-5+(-24)=-29</font></td></tr><tr><td  align="center"><font color=black>-6</font></td><td  align="center"><font color=black>-20</font></td><td  align="center"><font color=black>-6+(-20)=-26</font></td></tr><tr><td  align="center"><font color=black>-8</font></td><td  align="center"><font color=black>-15</font></td><td  align="center"><font color=black>-8+(-15)=-23</font></td></tr><tr><td  align="center"><font color=black>-10</font></td><td  align="center"><font color=black>-12</font></td><td  align="center"><font color=black>-10+(-12)=-22</font></td></tr></table>



From the table, we can see that the two numbers {{{8}}} and {{{15}}} add to {{{23}}} (the middle coefficient).



So the two numbers {{{8}}} and {{{15}}} both multiply to {{{120}}} <font size=4><b>and</b></font> add to {{{23}}}



Now replace the middle term {{{23x}}} with {{{8x+15x}}}. Remember, {{{8}}} and {{{15}}} add to {{{23}}}. So this shows us that {{{8x+15x=23x}}}.



{{{10x^2+highlight(8x+15x)+12}}} Replace the second term {{{23x}}} with {{{8x+15x}}}.



{{{(10x^2+8x)+(15x+12)}}} Group the terms into two pairs.



{{{2x(5x+4)+(15x+12)}}} Factor out the GCF {{{2x}}} from the first group.



{{{2x(5x+4)+3(5x+4)}}} Factor out {{{3}}} 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.



{{{(2x+3)(5x+4)}}} Combine like terms. Or factor out the common term {{{5x+4}}}


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Answer:



So {{{10x^2+23x+12}}} factors to {{{(2x+3)(5x+4)}}}.



Note: you can check the answer by FOILing {{{(2x+3)(5x+4)}}} to get {{{10x^2+23x+12}}} or by graphing the original expression and the answer (the two graphs should be identical).