The equation
\[
x^{2} - 2\mathrm{i}x + q = 0
\]
with a parameter \(q\in \mathbb{C}\)
has a solution \(x_{1} = 1 + 2\mathrm{i}\). Find
the second solution \(x_{2}\)
and the parameter \(q\).
Find the values of the parameter \(m\in \mathbb{C}\)
which guarantee that the following quadratic equation has a double solution.
\[
mx^{2} - 2x - 1 + \mathrm{i} = 0
\]
Establish the values of the parameter \(t\)
which ensure that the equation
\[
x^{2} + tx + t + 8 = 0
\]
with an unknown \(x\)
has complex solutions with a nonzero imaginary part.