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<選填題>已知 \( \vec{a} = (1,2,3), \vec{b} = (-1,1,2), \vec{c} = (3,5,6), \vec{d} = (4,-5,-11) \)，若 \( \vec{d} = x\vec{a} + y\vec{b} + z\vec{c} \)，則 \( x + y + z = \underline{\phantom{a}} \)。