Question 119704


Looking at {{{16x^2-2x-3}}} we can see that the first term is {{{16x^2}}} and the last term is {{{-3}}} where the coefficients are 16 and -3 respectively.


Now multiply the first coefficient 16 and the last coefficient -3 to get -48. Now what two numbers multiply to -48 and add to the  middle coefficient -2? Let's list all of the factors of -48:




Factors of -48:

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


-1,-2,-3,-4,-6,-8,-12,-16,-24,-48 ...List the negative factors as well. This will allow us to find all possible combinations


These factors pair up and multiply to -48

(1)*(-48)

(2)*(-24)

(3)*(-16)

(4)*(-12)

(6)*(-8)

(-1)*(48)

(-2)*(24)

(-3)*(16)

(-4)*(12)

(-6)*(8)


note: remember, the product of a negative and a positive number is a negative number



Now which of these pairs add to -2? Lets make a table of all of the pairs of factors we multiplied and see which two numbers add to -2


<table border="1"><th>First Number</th><th>Second Number</th><th>Sum</th><tr><td align="center">1</td><td align="center">-48</td><td>1+(-48)=-47</td></tr><tr><td align="center">2</td><td align="center">-24</td><td>2+(-24)=-22</td></tr><tr><td align="center">3</td><td align="center">-16</td><td>3+(-16)=-13</td></tr><tr><td align="center">4</td><td align="center">-12</td><td>4+(-12)=-8</td></tr><tr><td align="center">6</td><td align="center">-8</td><td>6+(-8)=-2</td></tr><tr><td align="center">-1</td><td align="center">48</td><td>-1+48=47</td></tr><tr><td align="center">-2</td><td align="center">24</td><td>-2+24=22</td></tr><tr><td align="center">-3</td><td align="center">16</td><td>-3+16=13</td></tr><tr><td align="center">-4</td><td align="center">12</td><td>-4+12=8</td></tr><tr><td align="center">-6</td><td align="center">8</td><td>-6+8=2</td></tr></table>



From this list we can see that 6 and -8 add up to -2 and multiply to -48



Now looking at the expression {{{16x^2-2x-3}}}, replace {{{-2x}}} with {{{6x+-8x}}} (notice {{{6x+-8x}}} adds up to {{{-2x}}}. So it is equivalent to {{{-2x}}})


{{{16x^2+highlight(6x+-8x)+-3}}}



Now let's factor {{{16x^2+6x-8x-3}}} by grouping:



{{{(16x^2+6x)+(-8x-3)}}} Group like terms



{{{2x(8x+3)-1(8x+3)}}} Factor out the GCF of {{{2x}}} out of the first group. Factor out the GCF of {{{-1}}} out of the second group



{{{(2x-1)(8x+3)}}} Since we have a common term of {{{8x+3}}}, we can combine like terms


So {{{16x^2+6x-8x-3}}} factors to {{{(2x-1)(8x+3)}}}



So this also means that {{{16x^2-2x-3}}} factors to {{{(2x-1)(8x+3)}}} (since {{{16x^2-2x-3}}} is equivalent to {{{16x^2+6x-8x-3}}})




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     Answer:

So {{{16x^2-2x-3}}} factors to {{{(2x-1)(8x+3)}}}