$(7)$ Write all calculations to find real$-$valued fundamental solutions of the differential equation

$x^{\text{'}}=Ax,A=\left[\begin{array}{cc}-1& 25\\ -1& -1\end{array}\right]$

b$)$ Write all calculations needed to find the solution $x(t)$ of the initial value problem

$x^{\text{'}}=Ax,x(0)=\left[\begin{array}{c}2\\ 1\end{array}\right]$