Calculus 3 : Vectors and Vector Operations

Study concepts, example questions & explanations for Calculus 3

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Example Questions

Example Question #2353 : Calculus 3

Given the following two vectors, \displaystyle \overrightarrow{a}=\widehat{i}+2\widehat{j}+3\widehat{k} and \displaystyle \overrightarrow{b}=3\widehat{i}+2\widehat{j}+\widehat{k}, calculate the dot product between them,\displaystyle \overrightarrow{a}\cdot\overrightarrow{b}.

Possible Answers:

\displaystyle 0

\displaystyle 36

\displaystyle 10

\displaystyle 11

\displaystyle 49

Correct answer:

\displaystyle 10

Explanation:

The dot product of a paired set of vectors can be found by summing up the individual products of the multiplications between matched directional vectors.

\displaystyle \overrightarrow{a}=a_1\widehat{x_1}+a_2\widehat{x_2}+a_3\widehat{x_3}+...+a_n\widehat{x_n}

\displaystyle \overrightarrow{b}=b_1\widehat{x_1}+b_2\widehat{x_2}+b_3\widehat{x_3}+...+b_n\widehat{x_n}

\displaystyle \overrightarrow{a}\cdot\overrightarrow{b}=a_1b_1+a_2b_2+a_3b_3+...+a_nb_n

Note that the dot product is a scalar value rather than a vector; there's no directional term.

Now considering our problem, we're given the vectors \displaystyle \overrightarrow{a}=\widehat{i}+2\widehat{j}+3\widehat{k} and \displaystyle \overrightarrow{b}=3\widehat{i}+2\widehat{j}+\widehat{k}

The dot product can be found following the example above:

\displaystyle \overrightarrow{a}\cdot\overrightarrow{b}=(3)+(4)+(3)=10

Example Question #2351 : Calculus 3

Given the following two vectors, \displaystyle \overrightarrow{a}=\widehat{i}+4\widehat{j}+5\widehat{k} and \displaystyle \overrightarrow{b}=2\widehat{i}-3\widehat{k}, calculate the dot product between them,\displaystyle \overrightarrow{a}\cdot\overrightarrow{b}.

Possible Answers:

\displaystyle 11

\displaystyle 15

\displaystyle -13

\displaystyle -9

\displaystyle -10

Correct answer:

\displaystyle -13

Explanation:

The dot product of a paired set of vectors can be found by summing up the individual products of the multiplications between matched directional vectors.

\displaystyle \overrightarrow{a}=a_1\widehat{x_1}+a_2\widehat{x_2}+a_3\widehat{x_3}+...+a_n\widehat{x_n}

\displaystyle \overrightarrow{b}=b_1\widehat{x_1}+b_2\widehat{x_2}+b_3\widehat{x_3}+...+b_n\widehat{x_n}

\displaystyle \overrightarrow{a}\cdot\overrightarrow{b}=a_1b_1+a_2b_2+a_3b_3+...+a_nb_n

Note that the dot product is a scalar value rather than a vector; there's no directional term.

Now considering our problem, we're given the vectors \displaystyle \overrightarrow{a}=\widehat{i}+4\widehat{j}+5\widehat{k} and \displaystyle \overrightarrow{b}=2\widehat{i}-3\widehat{k}

The dot product can be found following the example above:

\displaystyle \overrightarrow{a}\cdot\overrightarrow{b}=(2)+(0)+(-15)=-13

Example Question #31 : Dot Product

Find the dot product between the two vectors. 

\displaystyle u=< 1,2,1>

\displaystyle v=< 0,-3,-7>

Possible Answers:

\displaystyle 4

\displaystyle -6

\displaystyle 0

\displaystyle -13

Correct answer:

\displaystyle -13

Explanation:

The dot product for 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

Fo the given vectors 

\displaystyle u=< 1,2,1>

\displaystyle v=< 0,-3,-7>

\displaystyle u\bullet v =< 1,2,1>\bullet < 0,-3,-7>

\displaystyle =1*0+2*(-3)+1*(-7)

\displaystyle =0-6-7

\displaystyle =-13

Example Question #351 : Vectors And Vector Operations

Find the dot product of the two vectors. 

\displaystyle u=< 7,10>

\displaystyle v=< 3,7>

Possible Answers:

\displaystyle 700

\displaystyle 91

\displaystyle 1470

\displaystyle 79

Correct answer:

\displaystyle 91

Explanation:

The dot product for two vectors \displaystyle < a_1,a_2> and \displaystyle < b_1,b_2>

is defined as \displaystyle a_1*b_1+a_2*b_2

Fo the given vectors 

\displaystyle u=< 7,10>

\displaystyle v=< 3,7>

\displaystyle u\bullet v = < 7,10>\bullet < 3,7>

\displaystyle =7*3+10*7

\displaystyle =21+70

\displaystyle =91

Example Question #351 : Vectors And Vector Operations

Find the dot product \displaystyle v\cdot w of the two vectors

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

\displaystyle w=(0,5,3)

Possible Answers:

\displaystyle 1

\displaystyle 5

\displaystyle 2

\displaystyle -1

Correct answer:

\displaystyle 1

Explanation:

To find the dot product \displaystyle v\cdot w, we calculate

\displaystyle v\cdot w=1\cdot 0+(-1)\cdot 5+2\cdot 3=-5+6=1

Example Question #41 : Dot Product

Given the following two vectors, \displaystyle \overrightarrow{a}=1\widehat{i}+11\widehat{j} and \displaystyle \overrightarrow{b}=15\widehat{i}-2\widehat{j}, calculate the dot product between them,\displaystyle \overrightarrow{a}\cdot\overrightarrow{b}.

Possible Answers:

\displaystyle 37

\displaystyle -7

\displaystyle -156

\displaystyle 156

\displaystyle 52

Correct answer:

\displaystyle -7

Explanation:

The dot product of a paired set of vectors can be found by summing up the individual products of the multiplications between matched directional vectors.

\displaystyle \overrightarrow{a}=a_1\widehat{x_1}+a_2\widehat{x_2}+a_3\widehat{x_3}+...+a_n\widehat{x_n}

\displaystyle \overrightarrow{b}=b_1\widehat{x_1}+b_2\widehat{x_2}+b_3\widehat{x_3}+...+b_n\widehat{x_n}

\displaystyle \overrightarrow{a}\cdot\overrightarrow{b}=a_1b_1+a_2b_2+a_3b_3+...+a_nb_n

Note that the dot product is a scalar value rather than a vector; there's no directional term.

Now considering our problem, we're given the vectors \displaystyle \overrightarrow{a}=1\widehat{i}+11\widehat{j} and \displaystyle \overrightarrow{b}=15\widehat{i}-2\widehat{j}

The dot product can be found following the example above:

\displaystyle \overrightarrow{a}\cdot\overrightarrow{b}=(15)+(-22)=-7

Example Question #2352 : Calculus 3

Given the following two vectors, \displaystyle \overrightarrow{a}=7\widehat{i}-3\widehat{j} and \displaystyle \overrightarrow{b}=2\widehat{i}-\widehat{j}, calculate the dot product between them,\displaystyle \overrightarrow{a}\cdot\overrightarrow{b}.

Possible Answers:

\displaystyle 11

\displaystyle 23

\displaystyle 15

\displaystyle 17

\displaystyle -9

Correct answer:

\displaystyle 17

Explanation:

The dot product of a paired set of vectors can be found by summing up the individual products of the multiplications between matched directional vectors.

\displaystyle \overrightarrow{a}=a_1\widehat{x_1}+a_2\widehat{x_2}+a_3\widehat{x_3}+...+a_n\widehat{x_n}

\displaystyle \overrightarrow{b}=b_1\widehat{x_1}+b_2\widehat{x_2}+b_3\widehat{x_3}+...+b_n\widehat{x_n}

\displaystyle \overrightarrow{a}\cdot\overrightarrow{b}=a_1b_1+a_2b_2+a_3b_3+...+a_nb_n

Note that the dot product is a scalar value rather than a vector; there's no directional term.

Now considering our problem, we're given the vectors \displaystyle \overrightarrow{a}=7\widehat{i}-3\widehat{j} and \displaystyle \overrightarrow{b}=2\widehat{i}-\widehat{j}

The dot product can be found following the example above:

\displaystyle \overrightarrow{a}\cdot\overrightarrow{b}=(14)+(3)=17

Example Question #2353 : Calculus 3

Given the following two vectors, \displaystyle \overrightarrow{a}=-4\widehat{i}+8\widehat{j} and \displaystyle \overrightarrow{b}=6\widehat{i}+6\widehat{j}, calculate the dot product between them,\displaystyle \overrightarrow{a}\cdot\overrightarrow{b}.

Possible Answers:

\displaystyle -72

\displaystyle -42

\displaystyle 56

\displaystyle 24

\displaystyle 48

Correct answer:

\displaystyle 24

Explanation:

The dot product of a paired set of vectors can be found by summing up the individual products of the multiplications between matched directional vectors.

\displaystyle \overrightarrow{a}=a_1\widehat{x_1}+a_2\widehat{x_2}+a_3\widehat{x_3}+...+a_n\widehat{x_n}

\displaystyle \overrightarrow{b}=b_1\widehat{x_1}+b_2\widehat{x_2}+b_3\widehat{x_3}+...+b_n\widehat{x_n}

\displaystyle \overrightarrow{a}\cdot\overrightarrow{b}=a_1b_1+a_2b_2+a_3b_3+...+a_nb_n

Note that the dot product is a scalar value rather than a vector; there's no directional term.

Now considering our problem, we're given the vectors \displaystyle \overrightarrow{a}=-4\widehat{i}+8\widehat{j} and \displaystyle \overrightarrow{b}=6\widehat{i}+6\widehat{j}

The dot product can be found following the example above:

\displaystyle \overrightarrow{a}\cdot\overrightarrow{b}=(-24)+(48)=24

Example Question #2361 : Calculus 3

Given the following two vectors, \displaystyle \overrightarrow{a}=11\widehat{i}+17\widehat{j} and \displaystyle \overrightarrow{b}=3\widehat{i}-2\widehat{j}, calculate the dot product between them,\displaystyle \overrightarrow{a}\cdot\overrightarrow{b}.

Possible Answers:

\displaystyle 13

\displaystyle 5

\displaystyle 12

\displaystyle -6

\displaystyle -1

Correct answer:

\displaystyle -1

Explanation:

The dot product of a paired set of vectors can be found by summing up the individual products of the multiplications between matched directional vectors.

\displaystyle \overrightarrow{a}=a_1\widehat{x_1}+a_2\widehat{x_2}+a_3\widehat{x_3}+...+a_n\widehat{x_n}

\displaystyle \overrightarrow{b}=b_1\widehat{x_1}+b_2\widehat{x_2}+b_3\widehat{x_3}+...+b_n\widehat{x_n}

\displaystyle \overrightarrow{a}\cdot\overrightarrow{b}=a_1b_1+a_2b_2+a_3b_3+...+a_nb_n

Note that the dot product is a scalar value rather than a vector; there's no directional term.

Now considering our problem, we're given the vectors \displaystyle \overrightarrow{a}=11\widehat{i}+17\widehat{j} and \displaystyle \overrightarrow{b}=3\widehat{i}-2\widehat{j}

The dot product can be found following the example above:

\displaystyle \overrightarrow{a}\cdot\overrightarrow{b}=(33)+(-34)=-1

Example Question #352 : Vectors And Vector Operations

Given the following two vectors, \displaystyle \overrightarrow{a}=11\widehat{i}+3\widehat{j} and \displaystyle \overrightarrow{b}=10\widehat{i}+6\widehat{j}, calculate the dot product between them,\displaystyle \overrightarrow{a}\cdot\overrightarrow{b}.

Possible Answers:

\displaystyle 49

\displaystyle 154

\displaystyle 33

\displaystyle 96

\displaystyle 128

Correct answer:

\displaystyle 128

Explanation:

The dot product of a paired set of vectors can be found by summing up the individual products of the multiplications between matched directional vectors.

\displaystyle \overrightarrow{a}=a_1\widehat{x_1}+a_2\widehat{x_2}+a_3\widehat{x_3}+...+a_n\widehat{x_n}

\displaystyle \overrightarrow{b}=b_1\widehat{x_1}+b_2\widehat{x_2}+b_3\widehat{x_3}+...+b_n\widehat{x_n}

\displaystyle \overrightarrow{a}\cdot\overrightarrow{b}=a_1b_1+a_2b_2+a_3b_3+...+a_nb_n

Note that the dot product is a scalar value rather than a vector; there's no directional term.

Now considering our problem, we're given the vectors \displaystyle \overrightarrow{a}=11\widehat{i}+3\widehat{j} and \displaystyle \overrightarrow{b}=10\widehat{i}+6\widehat{j}

The dot product can be found following the example above:

\displaystyle \overrightarrow{a}\cdot\overrightarrow{b}=(110)+(18)=128

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