Question 88267
Take half of the x coefficient -2 to get -1 like this

{{{-2/2=-1}}}


Now square -1 


{{{(-1)^2=1}}}


Answer:


So the term to add is 1


Notice if we factor


{{{x^2-2x+1}}}


we get 


{{{(x-1)(x-1)=(x-1)^2}}} 


and this verifies our answer