Question 987166
.
(x - (1+2i))*(x - (1-2i)).


The constant term is the product  (1+2i)*(1-2i) = {{{1^2}}} - {{{(2i)^2}}} = 1 - 4*(-1) = 1 + 4 = 5.


The coefficient at &nbsp;<B>x</B> &nbsp;is &nbsp;-[(1+2i) + (1-2i)] = -2.


Hence, &nbsp;the quadratic equation is 


{{{x^2}}} - {{{2x}}} + {{{5}}} = {{{0}}}.