Question 942775
1+i is a root of P(x) --> 1-i is also a root of P(x)


The sum of the roots of P(x) is -1, so (1+i) + (1-i) + r = -1 --> r = -3. So -3 is also a root of P(x) (you can check this).


Then P(x) = (x - (1+i))(x - (1-i))(x+3).