Calculus 3 : Calculus 3

Study concepts, example questions & explanations for Calculus 3

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Example Questions

Example Question #63 : Dot Product

Given the following two vectors, \(\displaystyle \overrightarrow{a}=6\widehat{i}-8\widehat{j}+11\widehat{k}\) and \(\displaystyle \overrightarrow{b}=4\widehat{i}+\widehat{j}-2\widehat{k}\), calculate the dot product between them,\(\displaystyle \overrightarrow{a}\cdot\overrightarrow{b}\).

Possible Answers:

\(\displaystyle 14\)

\(\displaystyle -6\)

\(\displaystyle 54\)

\(\displaystyle -11\)

\(\displaystyle 8\)

Correct answer:

\(\displaystyle -6\)

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 \(\displaystyle \overrightarrow{a}=6\widehat{i}-8\widehat{j}+11\widehat{k}\) and \(\displaystyle \overrightarrow{b}=4\widehat{i}+\widehat{j}-2\widehat{k}\)

The dot product can be found following the example above:

\(\displaystyle \overrightarrow{a}\cdot\overrightarrow{b}=(24)+(-8)+(-22)=-6\)

Example Question #379 : Vectors And Vector Operations

Given the following two vectors, \(\displaystyle \overrightarrow{a}=\widehat{i}+5\widehat{j}+8\widehat{k}\) and \(\displaystyle \overrightarrow{b}=-2\widehat{i}+2\widehat{j}-\widehat{k}\), calculate the dot product between them,\(\displaystyle \overrightarrow{a}\cdot\overrightarrow{b}\).

Possible Answers:

\(\displaystyle 4\)

\(\displaystyle 20\)

\(\displaystyle 0\)

\(\displaystyle -2\)

\(\displaystyle 16\)

Correct answer:

\(\displaystyle 0\)

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 \(\displaystyle \overrightarrow{a}=\widehat{i}+5\widehat{j}+8\widehat{k}\) and \(\displaystyle \overrightarrow{b}=-2\widehat{i}+2\widehat{j}-\widehat{k}\)

The dot product can be found following the example above:

\(\displaystyle \overrightarrow{a}\cdot\overrightarrow{b}=(-2)+(10)+(-8)=0\)

Observe from this zero result that the two vectors must be perpendicular!

Example Question #64 : Dot Product

Given the following two vectors, \(\displaystyle \overrightarrow{a}=\begin{bmatrix} 1\\-5 \\3 \end{bmatrix}\) and \(\displaystyle \overrightarrow{b}=\begin{bmatrix} -2\\ 5\\6 \end{bmatrix}\), calculate the dot product between them,\(\displaystyle \overrightarrow{a}\cdot\overrightarrow{b}\).

Possible Answers:

\(\displaystyle -7\)

\(\displaystyle 17\)

\(\displaystyle 13\)

\(\displaystyle -9\)

\(\displaystyle 8\)

Correct answer:

\(\displaystyle -9\)

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.

\(\displaystyle \overrightarrow{a}=\begin{bmatrix} a_1\\a_2 \\ ...\\ a_n \end{bmatrix}\)

\(\displaystyle \overrightarrow{b}=\begin{bmatrix}b_1 \\b_2 \\...\\b_n \end{bmatrix}\)

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

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 

\(\displaystyle \overrightarrow{a}=\begin{bmatrix} 1\\-5 \\3 \end{bmatrix}\) and \(\displaystyle \overrightarrow{b}=\begin{bmatrix} -2\\ 5\\6 \end{bmatrix}\)

The dot product can be found following the example above:

\(\displaystyle \overrightarrow{a}\cdot\overrightarrow{b}=-2-25+18=-9\)

Example Question #65 : Dot Product

Given the following two vectors, \(\displaystyle \overrightarrow{a}=\begin{bmatrix} -8\\-6 \\-6 \end{bmatrix}\) and \(\displaystyle \overrightarrow{b}=\begin{bmatrix} 4\\-2 \\6 \end{bmatrix}\), calculate the dot product between them,\(\displaystyle \overrightarrow{a}\cdot\overrightarrow{b}\).

Possible Answers:

\(\displaystyle -80\)

\(\displaystyle 64\)

\(\displaystyle -56\)

\(\displaystyle 32\)

\(\displaystyle -28\)

Correct answer:

\(\displaystyle -56\)

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.

\(\displaystyle \overrightarrow{a}=\begin{bmatrix} a_1\\a_2 \\ ...\\ a_n \end{bmatrix}\)

\(\displaystyle \overrightarrow{b}=\begin{bmatrix}b_1 \\b_2 \\...\\b_n \end{bmatrix}\)

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

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

\(\displaystyle \overrightarrow{a}=\begin{bmatrix} -8\\-6 \\-6 \end{bmatrix}\) and \(\displaystyle \overrightarrow{b}=\begin{bmatrix} 4\\-2 \\6 \end{bmatrix}\)

The dot product can be found following the example above:

\(\displaystyle \overrightarrow{a}\cdot\overrightarrow{b}=-32+12-36=-56\)

Example Question #66 : Dot Product

Given the following two vectors, \(\displaystyle \overrightarrow{a}=\begin{bmatrix} 0\\ -3\\0 \end{bmatrix}\) and \(\displaystyle \overrightarrow{b}=\begin{bmatrix} 5\\7 \\8 \end{bmatrix}\), calculate the dot product between them,\(\displaystyle \overrightarrow{a}\cdot\overrightarrow{b}\).

Possible Answers:

\(\displaystyle 25\)

\(\displaystyle -15\)

\(\displaystyle 17\)

\(\displaystyle -24\)

\(\displaystyle -21\)

Correct answer:

\(\displaystyle -21\)

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.

\(\displaystyle \overrightarrow{a}=\begin{bmatrix} a_1\\a_2 \\ ...\\ a_n \end{bmatrix}\)

\(\displaystyle \overrightarrow{b}=\begin{bmatrix}b_1 \\b_2 \\...\\b_n \end{bmatrix}\)

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

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

\(\displaystyle \overrightarrow{a}=\begin{bmatrix} 0\\ -3\\0 \end{bmatrix}\) and \(\displaystyle \overrightarrow{b}=\begin{bmatrix} 5\\7 \\8 \end{bmatrix}\)

The dot product can be found following the example above:

\(\displaystyle \overrightarrow{a}\cdot\overrightarrow{b}=0-21+0=-21\)

Example Question #67 : Dot Product

Given the following two vectors, \(\displaystyle \overrightarrow{a}=\begin{bmatrix} -1\\7 \\5 \end{bmatrix}\) and \(\displaystyle \overrightarrow{b}=\begin{bmatrix} 0\\0 \\5 \end{bmatrix}\), calculate the dot product between them,\(\displaystyle \overrightarrow{a}\cdot\overrightarrow{b}\).

Possible Answers:

\(\displaystyle 65\)

\(\displaystyle 35\)

\(\displaystyle -5\)

\(\displaystyle 55\)

\(\displaystyle 25\)

Correct answer:

\(\displaystyle 25\)

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.

\(\displaystyle \overrightarrow{a}=\begin{bmatrix} a_1\\a_2 \\ ...\\ a_n \end{bmatrix}\)

\(\displaystyle \overrightarrow{b}=\begin{bmatrix}b_1 \\b_2 \\...\\b_n \end{bmatrix}\)

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

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

\(\displaystyle \overrightarrow{a}=\begin{bmatrix} -1\\7 \\5 \end{bmatrix}\) and \(\displaystyle \overrightarrow{b}=\begin{bmatrix} 0\\0 \\5 \end{bmatrix}\)

The dot product can be found following the example above:

\(\displaystyle \overrightarrow{a}\cdot\overrightarrow{b}=0+0+25=25\)

Example Question #68 : Dot Product

Given the following two vectors, \(\displaystyle \overrightarrow{a}=\begin{bmatrix}3 \\-7 \\-3 \end{bmatrix}\) and \(\displaystyle \overrightarrow{b}=\begin{bmatrix} -9\\-4 \\3 \end{bmatrix}\), calculate the dot product between them,\(\displaystyle \overrightarrow{a}\cdot\overrightarrow{b}\).

Possible Answers:

\(\displaystyle -64\)

\(\displaystyle 32\)

\(\displaystyle -8\)

\(\displaystyle 18\)

\(\displaystyle -36\)

Correct answer:

\(\displaystyle -8\)

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.

\(\displaystyle \overrightarrow{a}=\begin{bmatrix} a_1\\a_2 \\ ...\\ a_n \end{bmatrix}\)

\(\displaystyle \overrightarrow{b}=\begin{bmatrix}b_1 \\b_2 \\...\\b_n \end{bmatrix}\)

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

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

\(\displaystyle \overrightarrow{a}=\begin{bmatrix}3 \\-7 \\-3 \end{bmatrix}\) and \(\displaystyle \overrightarrow{b}=\begin{bmatrix} -9\\-4 \\3 \end{bmatrix}\)

The dot product can be found following the example above:

\(\displaystyle \overrightarrow{a}\cdot\overrightarrow{b}=-27+28-9=-8\)

Example Question #71 : Dot Product

Given the following two vectors, \(\displaystyle \overrightarrow{a}=\begin{bmatrix} 6\\ 4\\3 \end{bmatrix}\) and \(\displaystyle \overrightarrow{b}=\begin{bmatrix} 7\\6 \\1 \end{bmatrix}\), calculate the dot product between them,\(\displaystyle \overrightarrow{a}\cdot\overrightarrow{b}\).

Possible Answers:

\(\displaystyle 66\)

\(\displaystyle 45\)

\(\displaystyle 41\)

\(\displaystyle 27\)

\(\displaystyle 69\)

Correct answer:

\(\displaystyle 69\)

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.

\(\displaystyle \overrightarrow{a}=\begin{bmatrix} a_1\\a_2 \\ ...\\ a_n \end{bmatrix}\)

\(\displaystyle \overrightarrow{b}=\begin{bmatrix}b_1 \\b_2 \\...\\b_n \end{bmatrix}\)

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

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

\(\displaystyle \overrightarrow{a}=\begin{bmatrix} 6\\ 4\\3 \end{bmatrix}\) and \(\displaystyle \overrightarrow{b}=\begin{bmatrix} 7\\6 \\1 \end{bmatrix}\)

The dot product can be found following the example above:

\(\displaystyle \overrightarrow{a}\cdot\overrightarrow{b}=42+24+3=69\)

Example Question #71 : Dot Product

Given the following two vectors, \(\displaystyle \overrightarrow{a}=\begin{bmatrix} 9\\2 \\1 \end{bmatrix}\) and \(\displaystyle \overrightarrow{b}=\begin{bmatrix} -1\\4 \\-7 \end{bmatrix}\), calculate the dot product between them,\(\displaystyle \overrightarrow{a}\cdot\overrightarrow{b}\).

Possible Answers:

\(\displaystyle -8\)

\(\displaystyle 16\)

\(\displaystyle -24\)

\(\displaystyle 2\)

\(\displaystyle -14\)

Correct answer:

\(\displaystyle -8\)

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.

\(\displaystyle \overrightarrow{a}=\begin{bmatrix} a_1\\a_2 \\ ...\\ a_n \end{bmatrix}\)

\(\displaystyle \overrightarrow{b}=\begin{bmatrix}b_1 \\b_2 \\...\\b_n \end{bmatrix}\)

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

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

\(\displaystyle \overrightarrow{a}=\begin{bmatrix} 9\\2 \\1 \end{bmatrix}\) and \(\displaystyle \overrightarrow{b}=\begin{bmatrix} -1\\4 \\-7 \end{bmatrix}\)

The dot product can be found following the example above:

\(\displaystyle \overrightarrow{a}\cdot\overrightarrow{b}=-9+8-7=-8\)

Example Question #72 : Dot Product

Given the following two vectors, \(\displaystyle \overrightarrow{a}=\begin{bmatrix} 0\\2 \\-5 \end{bmatrix}\) and \(\displaystyle \overrightarrow{b}=\begin{bmatrix} 2\\-6 \\6 \end{bmatrix}\), calculate the dot product between them,\(\displaystyle \overrightarrow{a}\cdot\overrightarrow{b}\).

Possible Answers:

\(\displaystyle -42\)

\(\displaystyle 44\)

\(\displaystyle -56\)

\(\displaystyle -28\)

\(\displaystyle 28\)

Correct answer:

\(\displaystyle -42\)

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.

\(\displaystyle \overrightarrow{a}=\begin{bmatrix} a_1\\a_2 \\ ...\\ a_n \end{bmatrix}\)

\(\displaystyle \overrightarrow{b}=\begin{bmatrix}b_1 \\b_2 \\...\\b_n \end{bmatrix}\)

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

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

\(\displaystyle \overrightarrow{a}=\begin{bmatrix} 0\\2 \\-5 \end{bmatrix}\) and \(\displaystyle \overrightarrow{b}=\begin{bmatrix} 2\\-6 \\6 \end{bmatrix}\)

The dot product can be found following the example above:

\(\displaystyle \overrightarrow{a}\cdot\overrightarrow{b}=0-12-30=-42\)

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