Find \( \mathbf{u} \cdot \mathbf{v}, \mathbf{u} \cdot \mathbf{u},\|\mathbf{u}\|^{2},(\mathbf{u} \cdot \mathbf{v}) \mathbf{v} \), and \( \mathbf{u} \cdot(2 \mathbf{v}) \) \[ \mathbf{u}=\langle 7,11\rangle, \quad \mathbf{v}=\langle-2,3\rangle \]
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Let’s calculate each of the required expressions step by step. 1. **Dot Product \( \mathbf{u} \cdot \mathbf{v} \)** \[ \mathbf{u} \cdot \mathbf{v} = \langle 7, 11 \rangle \cdot \langle -2, 3 \rangle = 7 \cdot (-2) + 11 \cdot 3 = -14 + 33 = 19 \] 2. **Dot Product \( \mathbf{u} \cdot \mathbf{u} \)** \[ \mathbf{u} \cdot \mathbf{u} = \langle 7, 11 \rangle \cdot \langle 7, 11 \rangle = 7 \cdot 7 + 11 \cdot 11 = 49 + 121 = 170 \] 3. **Magnitude Squared \( \|\mathbf{u}\|^{2} \)** \[ \|\mathbf{u}\|^{2} = \mathbf{u} \cdot \mathbf{u} = 170 \quad (\text{Same as } \mathbf{u} \cdot \mathbf{u}) \] 4. **Vector \( (\mathbf{u} \cdot \mathbf{v}) \mathbf{v} \)** \[ (\mathbf{u} \cdot \mathbf{v}) \mathbf{v} = 19 \cdot \langle -2, 3 \rangle = \langle 19 \cdot (-2), 19 \cdot 3 \rangle = \langle -38, 57 \rangle \] 5. **Dot Product \( \mathbf{u} \cdot (2 \mathbf{v}) \)** \[ \mathbf{u} \cdot (2 \mathbf{v}) = \mathbf{u} \cdot \langle -4, 6 \rangle = \langle 7, 11 \rangle \cdot \langle -4, 6 \rangle = 7 \cdot (-4) + 11 \cdot 6 = -28 + 66 = 38 \] Putting it all together, we have: - \( \mathbf{u} \cdot \mathbf{v} = 19 \) - \( \mathbf{u} \cdot \mathbf{u} = 170 \) - \( \|\mathbf{u}\|^{2} = 170 \) - \( (\mathbf{u} \cdot \mathbf{v}) \mathbf{v} = \langle -38, 57 \rangle \) - \( \mathbf{u} \cdot (2 \mathbf{v}) = 38 \)