Draw a sketch to represent the vector. Refer to the vectors pictured here.
-$$\mathbf { i } + 3 \mathbf { j } , 8 \mathbf { i } - \mathbf { j }$$
A) $- 5$
B) 5
C) 11
D) 0

Question

Draw a sketch to represent the vector. Refer to the vectors pictured here. 
-$$\mathbf { i } + 3 \mathbf { j } , 8 \mathbf { i } - \mathbf { j }$$
A) $- 5$ 
B) 5 
C) 11 
D) 0

Quizplus · Accepted Answer

The dot product of two vectors $\mathbf{a} = a_1 \mathbf{i} + a_2 \mathbf{j}$ and $\mathbf{b} = b_1 \mathbf{i} + b_2 \mathbf{j}$ is given by $a_1b_1 + a_2b_2$. For $\mathbf{i} + 3\mathbf{j}$ and $8\mathbf{i} - \mathbf{j}$, the dot product is $1 \cdot 8 + 3 \cdot (-1) = 8 - 3 = 5$.

Draw a Sketch to Represent the Vector i+3j,8i−j\mathbf { i } + 3 \mathbf { j } , 8 \mathbf { i } - \mathbf { j }i+3j,8i−j

Draw a Sketch to Represent the Vector $\mathbf { i } + 3 \mathbf { j } , 8 \mathbf { i } - \mathbf { j }$