<image>The given function \( f(x) \) has a domain of \([-1, 5]\), with some corresponding values provided in the table, and the graph of its derivative \( y = f'(x) \) is shown in the image.
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(1) The local minimum value of \( f(x) \) is ___ ;
(2) If the function \( y = f(x) - a \) has 4 zeros, then the range of the real number \( a \) is ___ .
