Question 848747
Degree three, because you want exactly those three given roots.  I will do this only part-way:


The binomial factors of f will be {{{(x-2)(x-i)(x-(-i))}}}.  Multiply the two imaginary factors first:
{{{(x-i)( x-(-1))}}}
{{{(x-i)(x+i)}}}
{{{x^2-i^2}}}
{{{x^2-(-1)}}}
{{{x^2+1}}}
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So revise the function expression as {{{(x-2)(x^2+1)}}}
... and you can finish the rest.