Calculus 3 : Vectors and Vector Operations

Study concepts, example questions & explanations for Calculus 3

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Example Questions

Example Question #2243 : Calculus 3

Find the sum, \(\displaystyle u+v\)

\(\displaystyle u=< 4,16>\)

\(\displaystyle v=< 2,4>\)

Possible Answers:

\(\displaystyle < 2,12>\)

\(\displaystyle < 8,64>\)

\(\displaystyle < 6,20>\)

Correct answer:

\(\displaystyle < 6,20>\)

Explanation:

The sum of two vectors 

\(\displaystyle a=< a_1, a_2>\)

\(\displaystyle b=< b_1, b_2>\)

is defined as 

\(\displaystyle a+b=< a_1+b_1, a_2+b_2>\)

For the vectors in this problem

\(\displaystyle u+v=< 4+2, 16+4>\)

\(\displaystyle =< 6,20>\)

Example Question #2244 : Calculus 3

Perform the matrix operation \(\displaystyle \begin{bmatrix} 1&3 \\ 4&0 \end{bmatrix}+\begin{bmatrix} 3&9 \\ 17&38 \end{bmatrix}\)

Possible Answers:

\(\displaystyle \begin{bmatrix} 19&17 \\ 11& 10 \end{bmatrix}\)

\(\displaystyle \begin{bmatrix} -4&11 \\ 9&1 \end{bmatrix}\)

\(\displaystyle \begin{bmatrix} 5&3 \\ 17&38 \end{bmatrix}\)

\(\displaystyle \begin{bmatrix} 4&12 \\ 21 &38 \end{bmatrix}\)

Correct answer:

\(\displaystyle \begin{bmatrix} 4&12 \\ 21 &38 \end{bmatrix}\)

Explanation:

To find the sum \(\displaystyle \begin{bmatrix} a&b \\ c&d \end{bmatrix}+\begin{bmatrix} e& f\\ g &h \end{bmatrix}=\begin{bmatrix} a+e& b+f\\ c+g&d+h \end{bmatrix}\). Using the matrices in the problem statement, we get  \(\displaystyle \begin{bmatrix} 1+3& 3+9\\ 4+17 &0+38 \end{bmatrix}\)=\(\displaystyle \begin{bmatrix} 4&12 \\ 21 &38 \end{bmatrix}\)

Example Question #241 : Vectors And Vector Operations

Solve:

\(\displaystyle \left \langle 10, x\sin^2(y)\right \rangle+ \left \langle x, x\cos^2(y)\right \rangle\)

Possible Answers:

\(\displaystyle 10+2x\)

\(\displaystyle \left \langle 10+x, x\right \rangle\)

\(\displaystyle 10x+x^2\sin^2(y)\cos^2(y)\)

\(\displaystyle \left \langle 10x, x^2 \right \rangle\)

Correct answer:

\(\displaystyle \left \langle 10+x, x\right \rangle\)

Explanation:

When adding vectors, we simply add the corresponding components together:

\(\displaystyle \left \langle a, b\right \rangle + \left \langle c, d\right \rangle= \left \langle a+c, b+d\right \rangle\)

Our answer is

\(\displaystyle \left \langle 10+x, x\right \rangle\)

Note that our final answer is a vector.

Example Question #2246 : Calculus 3

Solve:

\(\displaystyle \left \langle z^2e^z, \cos(x)\right \rangle+ \left \langle ze^z, \sin(x)\right \rangle\)

Possible Answers:

\(\displaystyle e^z(z^2+z)+ \cos(x)+\sin(x)\)

\(\displaystyle \left \langle e^{2z}z^2z, \cos(x)\sin(x)\right \rangle\)

\(\displaystyle \left \langle e^z(z^2+z), \cos(x)+\sin(x)\right \rangle\)

\(\displaystyle \left \langle e^z(z^2+z),1\right \rangle\)

Correct answer:

\(\displaystyle \left \langle e^z(z^2+z), \cos(x)+\sin(x)\right \rangle\)

Explanation:

The sum of two vectors is the vector given by the sums of the respective components (for example, \(\displaystyle \left \langle a, b\right \rangle+\left \langle c, d\right \rangle=\left \langle a+c, b+d\right \rangle\)).

Our final answer is

\(\displaystyle \left \langle e^z(z^2+z), \cos(x)+\sin(x)\right \rangle\)

Example Question #2247 : Calculus 3

Perform the following vector operation: \(\displaystyle \left \langle 2xy,3y,z^3\right \rangle+\left \langle 7xy,9y,2z^3\right \rangle\)

Possible Answers:

\(\displaystyle \left \langle xy,y,3z^2\right \rangle\)

\(\displaystyle \left \langle 14xy,27y,2z^3\right \rangle\)

\(\displaystyle \left \langle 9xy,12y,3z^3\right \rangle\)

\(\displaystyle \left \langle 8xy,10y,3z^3\right \rangle\)

Correct answer:

\(\displaystyle \left \langle 9xy,12y,3z^3\right \rangle\)

Explanation:

The formula for adding two vectors \(\displaystyle a=\left \langle x_1,y_1,z_1\right \rangle\) and \(\displaystyle b=\left \langle x_2,y_2,z_2\right \rangle\) is \(\displaystyle a+b=\left \langle x_1+x_2,y_1+y_2,z_1+z_2\right \rangle\). Using the vectors from the problem statement, this becomes \(\displaystyle \left \langle 2xy+7xy,3y+9y,z^3+2z^3\right \rangle=\left \langle 9xy,12y,3z^3\right \rangle\)

Example Question #2248 : Calculus 3

Solve:

\(\displaystyle \left \langle \cos(yz), e^{z}\right \rangle + \left \langle 3\cos(yz), 2e^x\right \rangle\)

Possible Answers:

\(\displaystyle \left \langle 16\cos(yz)^2, e^{2z}+4e^{2x}\right \rangle\)

\(\displaystyle \left \langle 4\cos(yz), 3e^z\right \rangle\)

\(\displaystyle \left \langle 4\cos(yz), e^z+2e^x\right \rangle\)

\(\displaystyle 4\cos(yz)+e^z+2e^x\)

Correct answer:

\(\displaystyle \left \langle 4\cos(yz), e^z+2e^x\right \rangle\)

Explanation:

To add two vectors, we simply add the corresponding components (for example, \(\displaystyle \left \langle a, b\right \rangle+ \left \langle c, d\right \rangle=\left \langle a+c, b+d\right \rangle\))

Our final answer is

\(\displaystyle \left \langle 4\cos(yz), e^z+2e^x\right \rangle\)

Example Question #2249 : Calculus 3

Find the sum of the vectors \(\displaystyle \left \langle 3,y^2,\sin(z)\right \rangle\) and \(\displaystyle \left \langle 5,5y^2,3\sin(z)\right \rangle\)

Possible Answers:

\(\displaystyle \left \langle 6,6y^2,4\cos(z)\right \rangle\)

\(\displaystyle \left \langle 8,6y^2,4\sin(z)\right \rangle\)

\(\displaystyle \left \langle 7,6y^2,\sin(z)\right \rangle\textup{}\)

\(\displaystyle \left \langle 8,3y^2,4\sin(z)\right \rangle\,\)

Correct answer:

\(\displaystyle \left \langle 8,6y^2,4\sin(z)\right \rangle\)

Explanation:

To find the sum of two vectors \(\displaystyle a=\left \langle x_1,y_1,z_1\right \rangle\) and \(\displaystyle b=\left \langle x_2,y_2,z_2\right \rangle\) is \(\displaystyle a+b=\left \langle x_1+x_2,y_1+y_2,z_1+z_2\right \rangle\). Using the vectors we were given, we get \(\displaystyle a+b=\left \langle 3+5,y^2+5y^2,\sin(z)+3\sin(z)\right \rangle=\left \langle 8,6y^2,4\sin(z)\right \rangle\)

Example Question #2248 : Calculus 3

Find the sum of the vectors \(\displaystyle \left \langle 2,y^4,xyz)\right \rangle\) and \(\displaystyle \left \langle 10,3y^4,2xyz\right \rangle\)

Possible Answers:

\(\displaystyle \left \langle 12,4y^4,2xyz\right \rangle\)

\(\displaystyle \left \langle 11,4y^3,3xyz\right \rangle\)

\(\displaystyle \left \langle 12,4y^4,3xyz\right \rangle\)

\(\displaystyle \left \langle 12,y^4,3xyz\right \rangle\)

Correct answer:

\(\displaystyle \left \langle 12,4y^4,3xyz\right \rangle\)

Explanation:

To find the sum of two vectors \(\displaystyle a=\left \langle x_1,y_1,z_1\right \rangle\) and \(\displaystyle b=\left \langle x_2,y_2,z_2\right \rangle\) is \(\displaystyle a+b=\left \langle x_1+x_2,y_1+y_2,z_1+z_2\right \rangle\). Using the vectors we were given, we get \(\displaystyle a+b=\left \langle 2+10,y^4+3y^4,xyz+2xyz\right \rangle=\left \langle 12,4y^4,3xyz\right \rangle\)

Example Question #242 : Vectors And Vector Operations

Find the sum of the vectors \(\displaystyle \left \langle -4,3y^3,z\right \rangle\) and \(\displaystyle \left \langle 2,y^3,5z\right \rangle\)

Possible Answers:

\(\displaystyle -2+4y^3+6z\)

\(\displaystyle \left \langle -2,4y^3,6z\right \rangle\)

\(\displaystyle \left \langle -8,3y^6,5z^2\right \rangle\)

\(\displaystyle \left \langle -2,2y^3,3z\right \rangle\)

Correct answer:

\(\displaystyle \left \langle -2,4y^3,6z\right \rangle\)

Explanation:

To find the sum of two vectors \(\displaystyle a=\left \langle x_1,y_1,z_1\right \rangle\) and \(\displaystyle b=\left \langle x_2,y_2,z_2\right \rangle\) is \(\displaystyle a+b=\left \langle x_1+x_2,y_1+y_2,z_1+z_2\right \rangle\). Using the vectors we were given, we get \(\displaystyle a+b=\left \langle -4+2,3y^3+y^3,z+5z\right \rangle=\left \langle -2,4y^3,6z\right \rangle\)

Example Question #243 : Vectors And Vector Operations

Find the sum of the vectors \(\displaystyle \left \langle 5,3xyz,1\right \rangle\) and \(\displaystyle \left \langle -4,2xyz,-5\right \rangle\)

Possible Answers:

\(\displaystyle 1+5xyz+4\)

\(\displaystyle \left \langle 2,3xyz,4\right \rangle\)

\(\displaystyle \left \langle 0,xyz,1\right \rangle\)

\(\displaystyle \left \langle 1,5xyz,-4\right \rangle\)

Correct answer:

\(\displaystyle \left \langle 1,5xyz,-4\right \rangle\)

Explanation:

To find the sum of two vectors \(\displaystyle a=\left \langle x_1,y_1,z_1\right \rangle\) and \(\displaystyle b=\left \langle x_2,y_2,z_2\right \rangle\) is \(\displaystyle a+b=\left \langle x_1+x_2,y_1+y_2,z_1+z_2\right \rangle\). Using the vectors we were given, we get \(\displaystyle a+b=\left \langle 5-4,3xyz+2xyz,1-5\right \rangle=\left \langle 1,5xyz,-4\right \rangle\)

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