What are the eigen values of the following $$2x2$$ matrix? $$$\left[ {\matrix{ 2 & { - 1} \cr { - 4} & 5 \cr } } \right]$$$

Consider the following system of equations in three real variables $$x1, x2$$ and $$x3$$ :
$$2x1 - x2 + 3x3 = 1$$
$$3x1 + 2x2 + 5x3 = 2$$
$$ - x1 + 4x2 + x3 = 3$$
This system of equations has

Which one of the following graphs is NOT planar?

Consider the following code fragment:

if (fork() == 0)
{
   a = a + 5;
   printf("%d, %d \n", a, &a);
}
else
{
   a = a - 5;
   printf ("%d, %d \n", a, &a);
}

Let $$u,v$$ be the values printed by the parent process, and $$x,y$$ be the values printed by the child process. Which one of the following is TRUE?