Calculus 3 : Vector Addition

Study concepts, example questions & explanations for Calculus 3

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Example Questions

Example Question #1 : Vector Addition

Let \(\displaystyle \vec{a}=(1,2,3)\)\(\displaystyle \vec{b}=(10,-10,3)\), and \(\displaystyle \vec{c}=(0,0,1)\),

find \(\displaystyle \vec{a}+\vec{b}+\vec{c}\)

Possible Answers:

\(\displaystyle (0,0,1)\)

\(\displaystyle (11, -8, 7)\)

\(\displaystyle (7, -8,11)\)

\(\displaystyle (11, 0, 1)\)

\(\displaystyle (11, 7, -8)\)

Correct answer:

\(\displaystyle (11, -8, 7)\)

Explanation:

In order to find \(\displaystyle \vec{a}+\vec{b}+\vec{c}\), we need to add like components. \(\displaystyle \vec{a}+\vec{b}+\vec{c}=(1+10+0,2-10+0,3+3+1)=(11,-8,7)\)

Example Question #1 : Vector Addition

Given the vectors 

\(\displaystyle \small v=(2,3)\) and \(\displaystyle \small w=(2,100)\), compute \(\displaystyle \small v+w\).

Possible Answers:

\(\displaystyle \small \small \small v+w=(0,100)\)

\(\displaystyle \small \small \small v+w=(104,5)\)

\(\displaystyle \small \small v+w=(103,4)\)

\(\displaystyle \small \small v+w=(4,103)\)

Correct answer:

\(\displaystyle \small \small v+w=(4,103)\)

Explanation:

To add two vectors \(\displaystyle \small v,w\), we simply add their components:

\(\displaystyle \small \small \small v+w=(2,3)+(2,100)=(2+2,3+100)=(4,103)\)

Example Question #2 : Vector Addition

Given the vectors 

\(\displaystyle \small \small v=(0,10)\) and \(\displaystyle \small \small w=(-10,0)\), compute \(\displaystyle \small v+w\).

Possible Answers:

\(\displaystyle \small \small \small \small v+w=(10,10)\)

\(\displaystyle \small \small \small \small \small v+w=(10,-10)\)

\(\displaystyle \small \small \small \small v+w=(-10,10)\)

\(\displaystyle \small \small \small \small v+w=(0,0)\)

Correct answer:

\(\displaystyle \small \small \small \small v+w=(-10,10)\)

Explanation:

To add two vectors \(\displaystyle \small v,w\), we simply add their components:

\(\displaystyle \small \small \small \small v+w=(0,10)+(-10,0)=(0-10,10+0)=(-10,10)\)

Example Question #1 : Vector Addition

Find the sum of the vectors given below

\(\displaystyle \vec{A}= 4 \hat{x}-\hat{y}, \vec{B}=-3\hat{x}+10\hat{y}\)

Possible Answers:

\(\displaystyle \vec{A}+\vec{B}= \hat{x}+9\hat{y}\)

\(\displaystyle \vec{A}+\vec{B}= -\hat{x}-9\hat{y}\)

\(\displaystyle \vec{A}+\vec{B}= 3\hat{x}+7\hat{y}\)

\(\displaystyle \vec{A}+\vec{B}= 10\)

Correct answer:

\(\displaystyle \vec{A}+\vec{B}= \hat{x}+9\hat{y}\)

Explanation:

When adding vectors, it is important to note that the summation only occurs between terms that have the same coordinate direction \(\displaystyle \left( \hat{x}, \hat{y}, etc. \right)\).  Therefore, we find 

\(\displaystyle \vec{A}+\vec{B}= \left(4\hat{x}-1\hat{y} \right ) + \left( -3\hat{x}+10\hat{y}\right) = \hat{x}(4+(-3))+\hat{y}(-1+10) =\hat{x}+9\hat{y}\)

Example Question #5 : Vector Addition

Find the sum of the two vectors. 

\(\displaystyle u=< 1,0,0>\)

\(\displaystyle v=< 0,0,3>\)

Possible Answers:

\(\displaystyle < 1,0,3>\)

\(\displaystyle 4\)

\(\displaystyle 0\)

\(\displaystyle < 1,0,-3>\)

Correct answer:

\(\displaystyle < 1,0,3>\)

Explanation:

The sum of two vectors \(\displaystyle < a_1,a_2,a_3>\) and \(\displaystyle < b_1,b_2,b_3>\) is defined as

\(\displaystyle < a_1+b_1,a_2+b_2,a_3+b_3>\)

For the vectors 

\(\displaystyle u=< 1,0,0>\)

\(\displaystyle v=< 0,0,3>\)

\(\displaystyle u+v=< 1,0,0>+< 0,0,3>\)

\(\displaystyle =< 1+0,0+0,0+3>\)

\(\displaystyle =< 1,0,3>\)

Example Question #1 : Vector Addition

Given vectors

\(\displaystyle v=(1,-1,2)\)

\(\displaystyle w=(0,5,3)\)

find \(\displaystyle v+w\).

Possible Answers:

\(\displaystyle v+w=(5,1,4)\)

\(\displaystyle v+w=(1,2,3)\)

\(\displaystyle v+w=(0,5,3)\)

\(\displaystyle v+w=(1,4,5)\)

Correct answer:

\(\displaystyle v+w=(1,4,5)\)

Explanation:

To find the sum \(\displaystyle v+w\), we add their components:

\(\displaystyle v+w=(1,-1,2)+(0,5,3)=(1+0,-1+5,2+3)=(1,4,5)\)

Example Question #1 : Vector Addition

Given the vectors

\(\displaystyle v=(1,3)\)

\(\displaystyle w=(5,2)\)

find the sum \(\displaystyle v+w\).

Possible Answers:

\(\displaystyle v+w=(6,5)\)

\(\displaystyle v+w=(-4,1)\)

\(\displaystyle v+w=(4,-1)\)

\(\displaystyle v+w=(5,6)\)

Correct answer:

\(\displaystyle v+w=(6,5)\)

Explanation:

To find the sum \(\displaystyle v+w\) of the vectors

\(\displaystyle v=(1,3)\)

\(\displaystyle w=(5,2)\)

 we add their components:

\(\displaystyle v+w=(1,3)+(5,2)=(1+5,3+2)=(6,5)\)

Example Question #8 : Vector Addition

Add the following vectors:

\(\displaystyle \mathbf{u}+\mathbf{v}\)

Where

\(\displaystyle \mathbf{u}=12\mathbf{i}-7\mathbf{j}+10\mathbf{k}\),  \(\displaystyle \mathbf{v}=3\mathbf{i}+8\mathbf{j}-4\mathbf{k}\)

Possible Answers:

\(\displaystyle 8\mathbf{i}+\mathbf{j}+13\mathbf{k}\)

\(\displaystyle 9\mathbf{i}-15\mathbf{j}+14\mathbf{k}\)

\(\displaystyle 15\mathbf{i}+\mathbf{j}+6\mathbf{k}\)

\(\displaystyle 7\mathbf{i}+16\mathbf{j}-3\mathbf{k}\)

Correct answer:

\(\displaystyle 15\mathbf{i}+\mathbf{j}+6\mathbf{k}\)

Explanation:

Vector addition is done as follows:

\(\displaystyle \mathbf{u}+\mathbf{v}=(u_x+v_x)\mathbf{i}+(u_y+v_y)\mathbf{j}+(u_z+v_z)\mathbf{k}\)

For this problem:

\(\displaystyle \mathbf{u}+\mathbf{v}=(12+3)\mathbf{i}+((-7)+8)\mathbf{j}+(10+(-4))\mathbf{k}= 15\mathbf{i}+\mathbf{j}+6\mathbf{k}\)

Example Question #1 : Vector Addition

Add the vectors \(\displaystyle 3x+9y\) given:  \(\displaystyle x=\left \langle 3,-2\right \rangle\) and \(\displaystyle y=\left \langle -3,-6\right \rangle\)

Possible Answers:

\(\displaystyle \left \langle 0,-72\right \rangle\)

\(\displaystyle \left \langle -6,-60\right \rangle\)

\(\displaystyle \left \langle18,-60 \right \rangle\)

\(\displaystyle \left \langle-18,-60 \right \rangle\)

\(\displaystyle \left \langle -6,-72\right \rangle\)

Correct answer:

\(\displaystyle \left \langle-18,-60 \right \rangle\)

Explanation:

Multiply the vectors with the constants first.

Evaluate \(\displaystyle 3x\).

\(\displaystyle 3\left \langle 3,-2\right \rangle = \left \langle 9,-6\right \rangle\)

Evaluate \(\displaystyle 9y\).

\(\displaystyle 9\left \langle -3,-6\right \rangle =\left \langle -27, -54 \right \rangle\)

Add the vectors \(\displaystyle 3x+9y\).

\(\displaystyle \left \langle 9,-6\right \rangle+\left \langle -27, -54 \right \rangle = \left \langle-18,-60 \right \rangle\)

The answer is:  \(\displaystyle \left \langle-18,-60 \right \rangle\)

Example Question #10 : Vector Addition

Given the vectors 

\(\displaystyle \small v=(\pi,e)\)

\(\displaystyle \small w=(1,2)\)

find the sum \(\displaystyle \small v+w\).

Possible Answers:

\(\displaystyle \small \small v+w=(\pi+1,e+3)\)

\(\displaystyle \small \small v+w=(\pi+1,e^2)\)

\(\displaystyle \small \small v+w=(e+2,\pi+1)\)

\(\displaystyle \small v+w=(\pi+1,e+2)\)

Correct answer:

\(\displaystyle \small v+w=(\pi+1,e+2)\)

Explanation:

Given the vectors 

\(\displaystyle \small v=(\pi,e)\)

\(\displaystyle \small w=(1,2)\)

we can find the sum \(\displaystyle \small v+w\) by adding component by component:

\(\displaystyle \small \small v+w=(\pi,e)+(1,2)=(\pi+1,e+2)\)

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