Find the values of the real coefficients
\(a\),
\(b\) and
\(c\) such
that the quadratic equation
\[
ax^{2} + bx + c = 0
\]
has solution \(x_{1, 2} =\pm \mathrm{i}\frac{\sqrt{5}}
{3} \).
Find the values of the real coefficients
\(a\),
\(b\) and
\(c\) such
that the quadratic equation
\[
ax^{2} + bx + c = 0
\]
has solutions \(x_{1, 2} = 1\pm \frac{\mathrm{i}}
{2}\).
In the arithmetic sequence given by the first term
\(a_{1} = 4\) and the common
difference \(d = 2\)
find the sum of the first twelve terms of the sequence.