Problem

Use the given vectors to find $\mathbf{v} \cdot \mathbf{w}$ and $\mathbf{v} \cdot \mathbf{v}$.
\[
\mathbf{v}=6 \mathbf{i}-3 \mathbf{j}, \mathbf{w}=-2 \mathbf{i}-\mathbf{j}
\]

Answer

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Answer

Final Answer: \(\mathbf{v} \cdot \mathbf{w} = \boxed{-9}\) and \(\mathbf{v} \cdot \mathbf{v} = \boxed{45}\)

Steps

Step 1 :Given vectors are \(\mathbf{v}=6 \mathbf{i}-3 \mathbf{j}\), \(\mathbf{w}=-2 \mathbf{i}-\mathbf{j}\)

Step 2 :The dot product of two vectors can be calculated by multiplying the corresponding components of the vectors and then adding them together. For vectors in 2D, if \(\mathbf{v}=a \mathbf{i}+b \mathbf{j}\) and \(\mathbf{w}=c \mathbf{i}+d \mathbf{j}\), then \(\mathbf{v} \cdot \mathbf{w}=ac+bd\)

Step 3 :Substitute the given vectors into the formula, we get \(\mathbf{v} \cdot \mathbf{w}=(6*-2)+(-3*-1)\) and \(\mathbf{v} \cdot \mathbf{v}=(6*6)+(-3*-3)\)

Step 4 :Calculate the above expressions, we get \(\mathbf{v} \cdot \mathbf{w} = -9\) and \(\mathbf{v} \cdot \mathbf{v} = 45\)

Step 5 :Final Answer: \(\mathbf{v} \cdot \mathbf{w} = \boxed{-9}\) and \(\mathbf{v} \cdot \mathbf{v} = \boxed{45}\)

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