Question 185548


Looking at the expression {{{2x^2-7x+3}}}, we can see that the first coefficient is {{{2}}}, the second coefficient is {{{-7}}}, and the last term is {{{3}}}.



Now multiply the first coefficient {{{2}}} by the last term {{{3}}} to get {{{(2)(3)=6}}}.



Now the question is: what two whole numbers multiply to {{{6}}} (the previous product) <font size=4><b>and</b></font> add to the second coefficient {{{-7}}}?



To find these two numbers, we need to list <font size=4><b>all</b></font> of the factors of {{{6}}} (the previous product).



Factors of {{{6}}}:

1,2,3,6

-1,-2,-3,-6



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



These factors pair up and multiply to {{{6}}}.

1*6
2*3
(-1)*(-6)
(-2)*(-3)


Now let's add up each pair of factors to see if one pair adds to the middle coefficient {{{-7}}}:



<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>6</font></td><td  align="center"><font color=black>1+6=7</font></td></tr><tr><td  align="center"><font color=black>2</font></td><td  align="center"><font color=black>3</font></td><td  align="center"><font color=black>2+3=5</font></td></tr><tr><td  align="center"><font color=red>-1</font></td><td  align="center"><font color=red>-6</font></td><td  align="center"><font color=red>-1+(-6)=-7</font></td></tr><tr><td  align="center"><font color=black>-2</font></td><td  align="center"><font color=black>-3</font></td><td  align="center"><font color=black>-2+(-3)=-5</font></td></tr></table>



From the table, we can see that the two numbers {{{-1}}} and {{{-6}}} add to {{{-7}}} (the middle coefficient).



So the two numbers {{{-1}}} and {{{-6}}} both multiply to {{{6}}} <font size=4><b>and</b></font> add to {{{-7}}}



Now replace the middle term {{{-7x}}} with {{{-x-6x}}}. Remember, {{{-1}}} and {{{-6}}} add to {{{-7}}}. So this shows us that {{{-x-6x=-7x}}}.



{{{2x^2+highlight(-x-6x)+3}}} Replace the second term {{{-7x}}} with {{{-x-6x}}}.



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



{{{x(2x-1)+(-6x+3)}}} Factor out the GCF {{{x}}} from the first group.



{{{x(2x-1)-3(2x-1)}}} 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.



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


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Answer:



So {{{2x^2-7x+3}}} factors to {{{(x-3)(2x-1)}}}.



So {{{x-3}}} and {{{2x-1}}} are factors of {{{2x^2-7x+3}}}