Question 1204191
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This is something to do using trial-and-error.
It's implied that the numbers in question are integers.


Here's all of the ways to multiply to 5, using only integers.
1*5 = 5
(-1)*(-5) = 5
Luckily the list is really short. 


Then we add up each pair
1+5 = 6
-1+(-5) = -6


We find that there aren't any pairs of numbers that add to -4 and multiply to 5.


This will mean x^2-4x+5 cannot be factored over the rational numbers.


If you wanted, you can use the quadratic formula to solve x^2-4x+5 = 0
Doing so leads to "no real number solutions" since the discriminant is negative. 
This is further evidence there aren't pairs of integers that add to -4 and multiply to 5.
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