Question 1147942
Perfect-square trinomials are of the form:

{{{a^2x^2 +- 2abx + b^2}}}

and are expressed in squared-binomial form as:

{{{(ax +- b)^2}}}


you have {{{x^2-1x}}}, so {{{a=1}}} and {{{2ab=1}}}

take {{{2ab=1}}} and plug in {{{a=1}}}, then  solve for {{{b}}}

{{{2*1*b=1}}}

{{{b=1/2}}}


so, the last term to make the trinomial into a perfect square is {{{b=1/2}}}