Characteristic polynomial wont be used in solve

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When I try to find roots in a characteristic polynomial it gives me errors:

sage: #Diagonalmatrix
....: 
....: 
....: A=matrix([[1,-1,2],
....:         [-1,1,2],
....:         [2,2,-2]])
....: var('x')
....: poly=A.characteristic_polynomial()
....: eq1=solve(poly==0,x)
....:                                            
x                                                
--------------------------------------------------
TypeError        Traceback (most recent call last)
<ipython-input-86-fee7a7de2ea1> in <module>()
      7 var('x')
      8 poly=A.characteristic_polynomial()
----> 9 eq1=solve(poly==Integer(0),x)

/usr/lib/python2.7/site-packages/sage/symbolic/relation.pyc in solve(f, *args, **kwds)
    816 
    817     if not isinstance(f, (list, tuple)):
--> 818         raise TypeError("The first argument must be a symbolic expression or a list of symbolic expressions.")
    819 
    820     if len(f)==1:

TypeError: The first argument must be a symbolic expression or a list of symbolic expressions.
sage:

What can I do in order to use the polynomial in an equation I wish to solve?