Find the following expressions if \mathbf{a} = 2\mathbf{i} - 5\mathbf{k} , \mathbf{b} = \mathbf{i} +\mathbf{j} - 5\mathbf{k} , and \mathbf{c} = 4\mathbf{i} +2\mathbf{j} + 2\mathbf{k} .

** 1. ** \space \mathbf{a} \cdot \mathbf{b} =

** 2. **

** 3. **

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