Question 551103


Looking at the expression {{{3x^2+14x+16}}}, we can see that the first coefficient is {{{3}}}, the second coefficient is {{{14}}}, and the last term is {{{16}}}.



Now multiply the first coefficient {{{3}}} by the last term {{{16}}} to get {{{(3)(16)=48}}}.



Now the question is: what two whole numbers multiply to {{{48}}} (the previous product) <font size=4><b>and</b></font> add to the second coefficient {{{14}}}?



To find these two numbers, we need to list <font size=4><b>all</b></font> of the factors of {{{48}}} (the previous product).



Factors of {{{48}}}:

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

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



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



These factors pair up and multiply to {{{48}}}.

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


Now let's add up each pair of factors to see if one pair adds to the middle coefficient {{{14}}}:



<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>48</font></td><td  align="center"><font color=black>1+48=49</font></td></tr><tr><td  align="center"><font color=black>2</font></td><td  align="center"><font color=black>24</font></td><td  align="center"><font color=black>2+24=26</font></td></tr><tr><td  align="center"><font color=black>3</font></td><td  align="center"><font color=black>16</font></td><td  align="center"><font color=black>3+16=19</font></td></tr><tr><td  align="center"><font color=black>4</font></td><td  align="center"><font color=black>12</font></td><td  align="center"><font color=black>4+12=16</font></td></tr><tr><td  align="center"><font color=red>6</font></td><td  align="center"><font color=red>8</font></td><td  align="center"><font color=red>6+8=14</font></td></tr><tr><td  align="center"><font color=black>-1</font></td><td  align="center"><font color=black>-48</font></td><td  align="center"><font color=black>-1+(-48)=-49</font></td></tr><tr><td  align="center"><font color=black>-2</font></td><td  align="center"><font color=black>-24</font></td><td  align="center"><font color=black>-2+(-24)=-26</font></td></tr><tr><td  align="center"><font color=black>-3</font></td><td  align="center"><font color=black>-16</font></td><td  align="center"><font color=black>-3+(-16)=-19</font></td></tr><tr><td  align="center"><font color=black>-4</font></td><td  align="center"><font color=black>-12</font></td><td  align="center"><font color=black>-4+(-12)=-16</font></td></tr><tr><td  align="center"><font color=black>-6</font></td><td  align="center"><font color=black>-8</font></td><td  align="center"><font color=black>-6+(-8)=-14</font></td></tr></table>



From the table, we can see that the two numbers {{{6}}} and {{{8}}} add to {{{14}}} (the middle coefficient).



So the two numbers {{{6}}} and {{{8}}} both multiply to {{{48}}} <font size=4><b>and</b></font> add to {{{14}}}



Now replace the middle term {{{14x}}} with {{{6x+8x}}}. Remember, {{{6}}} and {{{8}}} add to {{{14}}}. So this shows us that {{{6x+8x=14x}}}.



{{{3x^2+highlight(6x+8x)+16}}} Replace the second term {{{14x}}} with {{{6x+8x}}}.



{{{(3x^2+6x)+(8x+16)}}} Group the terms into two pairs.



{{{3x(x+2)+(8x+16)}}} Factor out the GCF {{{3x}}} from the first group.



{{{3x(x+2)+8(x+2)}}} 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.



{{{(3x+8)(x+2)}}} Combine like terms. Or factor out the common term {{{x+2}}}



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Answer:



So {{{3x^2+14x+16}}} factors to {{{(3x+8)(x+2)}}}.



In other words, {{{3x^2+14x+16=(3x+8)(x+2)}}}.



Note: you can check the answer by expanding {{{(3x+8)(x+2)}}} to get {{{3x^2+14x+16}}} or by graphing the original expression and the answer (the two graphs should be identical).