Question 577749


Looking at the expression {{{64p^2-63p+16}}}, we can see that the first coefficient is {{{64}}}, the second coefficient is {{{-63}}}, and the last term is {{{16}}}.



Now multiply the first coefficient {{{64}}} by the last term {{{16}}} to get {{{(64)(16)=1024}}}.



Now the question is: what two whole numbers multiply to {{{1024}}} (the previous product) <font size=4><b>and</b></font> add to the second coefficient {{{-63}}}?



To find these two numbers, we need to list <font size=4><b>all</b></font> of the factors of {{{1024}}} (the previous product).



Factors of {{{1024}}}:

1,2,4,8,16,32,64,128,256,512,1024

-1,-2,-4,-8,-16,-32,-64,-128,-256,-512,-1024



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



These factors pair up and multiply to {{{1024}}}.

1*1024 = 1024
2*512 = 1024
4*256 = 1024
8*128 = 1024
16*64 = 1024
32*32 = 1024
(-1)*(-1024) = 1024
(-2)*(-512) = 1024
(-4)*(-256) = 1024
(-8)*(-128) = 1024
(-16)*(-64) = 1024
(-32)*(-32) = 1024


Now let's add up each pair of factors to see if one pair adds to the middle coefficient {{{-63}}}:



<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>1024</font></td><td  align="center"><font color=black>1+1024=1025</font></td></tr><tr><td  align="center"><font color=black>2</font></td><td  align="center"><font color=black>512</font></td><td  align="center"><font color=black>2+512=514</font></td></tr><tr><td  align="center"><font color=black>4</font></td><td  align="center"><font color=black>256</font></td><td  align="center"><font color=black>4+256=260</font></td></tr><tr><td  align="center"><font color=black>8</font></td><td  align="center"><font color=black>128</font></td><td  align="center"><font color=black>8+128=136</font></td></tr><tr><td  align="center"><font color=black>16</font></td><td  align="center"><font color=black>64</font></td><td  align="center"><font color=black>16+64=80</font></td></tr><tr><td  align="center"><font color=black>32</font></td><td  align="center"><font color=black>32</font></td><td  align="center"><font color=black>32+32=64</font></td></tr><tr><td  align="center"><font color=black>-1</font></td><td  align="center"><font color=black>-1024</font></td><td  align="center"><font color=black>-1+(-1024)=-1025</font></td></tr><tr><td  align="center"><font color=black>-2</font></td><td  align="center"><font color=black>-512</font></td><td  align="center"><font color=black>-2+(-512)=-514</font></td></tr><tr><td  align="center"><font color=black>-4</font></td><td  align="center"><font color=black>-256</font></td><td  align="center"><font color=black>-4+(-256)=-260</font></td></tr><tr><td  align="center"><font color=black>-8</font></td><td  align="center"><font color=black>-128</font></td><td  align="center"><font color=black>-8+(-128)=-136</font></td></tr><tr><td  align="center"><font color=black>-16</font></td><td  align="center"><font color=black>-64</font></td><td  align="center"><font color=black>-16+(-64)=-80</font></td></tr><tr><td  align="center"><font color=black>-32</font></td><td  align="center"><font color=black>-32</font></td><td  align="center"><font color=black>-32+(-32)=-64</font></td></tr></table>



From the table, we can see that there are no pairs of numbers which add to {{{-63}}}. So {{{64p^2-63p+16}}} cannot be factored.



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Answer:



So {{{64p^2-63p+16}}} doesn't factor at all (over the rational numbers).



So {{{64p^2-63p+16}}} is prime.