Two matrices with special eigenvalues We say $\lambda$ is an eigenvalue of a square matrix $A$ if
$Ax = \lambda x$.  
Now, i want two examples of a matrix like $A$.
The first one, $A$ should have just one eigenvalue which should be $0$.
The second one, $A$ should be a matrix in which $a_1,\dots,a_n$ are 
eigenvalues. ( They give $a_i$'s and want the matrix )  
Note : I have no idea how to find these matrices. I don't know where to start ...

So, with the hint andrew gave me, i solved the problem myself...
If a matrix is diagonal and $a_1,\dots,a_n$ are on the diagonal, then we have equations like :
($a_i-\lambda )(x_i)=0$
And one matrix which has zero as an eigenvalue and zero is its only eigenvalue is the zero matrix itself !!! ( For example, zero matrix in $M_2(\mathbb R)$ )
