Calculus 3 : Vectors and Vector Operations

Study concepts, example questions & explanations for Calculus 3

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Example Questions

Example Question #36 : Dot Product

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:

\(\displaystyle 10\)

\(\displaystyle 11\)

\(\displaystyle 36\)

\(\displaystyle 49\)

\(\displaystyle 0\)

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 #37 : Dot Product

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:

\(\displaystyle -9\)

\(\displaystyle 11\)

\(\displaystyle 15\)

\(\displaystyle -10\)

\(\displaystyle -13\)

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 #38 : Dot Product

Find the dot product between the two vectors. 

\(\displaystyle u=< 1,2,1>\)

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

Possible Answers:

\(\displaystyle -6\)

\(\displaystyle 4\)

\(\displaystyle -13\)

\(\displaystyle 0\)

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 #31 : Dot Product

Find the dot product of the two vectors. 

\(\displaystyle u=< 7,10>\)

\(\displaystyle v=< 3,7>\)

Possible Answers:

\(\displaystyle 79\)

\(\displaystyle 91\)

\(\displaystyle 1470\)

\(\displaystyle 700\)

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 #32 : Dot Product

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

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

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

Possible Answers:

\(\displaystyle 5\)

\(\displaystyle 1\)

\(\displaystyle 2\)

\(\displaystyle -1\)

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:

\(\displaystyle 37\)

\(\displaystyle -7\)

\(\displaystyle 52\)

\(\displaystyle -156\)

\(\displaystyle 156\)

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 #42 : Dot Product

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:

\(\displaystyle 15\)

\(\displaystyle 23\)

\(\displaystyle 17\)

\(\displaystyle 11\)

\(\displaystyle -9\)

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 #43 : Dot Product

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:

\(\displaystyle 48\)

\(\displaystyle 56\)

\(\displaystyle -42\)

\(\displaystyle -72\)

\(\displaystyle 24\)

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 #44 : Dot Product

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:

\(\displaystyle 13\)

\(\displaystyle 12\)

\(\displaystyle -6\)

\(\displaystyle 5\)

\(\displaystyle -1\)

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 #45 : Dot Product

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:

\(\displaystyle 154\)

\(\displaystyle 49\)

\(\displaystyle 96\)

\(\displaystyle 33\)

\(\displaystyle 128\)

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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