Calculus 3 : Calculus 3

Study concepts, example questions & explanations for Calculus 3

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Example Questions

Example Question #2451 : Calculus 3

Find the dot product between \displaystyle \left \langle x,-3,4z\right \rangle and \displaystyle \left \langle x,y,z\right \rangle

Possible Answers:

\displaystyle x^2+6y+4z^2

\displaystyle x^2-3y+4z^2

\displaystyle x^2-5y+5z^2

\displaystyle x^3+y+7z^2

Correct answer:

\displaystyle x^2-3y+4z^2

Explanation:

To find the dot product between 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 we use the formula \displaystyle a\cdot b=(x_1*x_2)+(y_1*y_2)+(z_1*z_2). Using the vectors in the problem statement, we get \displaystyle (x*x)+(-3*y)+(4z*z)=x^2-3y+4z^2

Example Question #2452 : Calculus 3

Consider the vector \displaystyle \mathbf{v}=\mathbf{i}+7\mathbf{j}+2\mathbf{k}.

Which of the following vectors are orthogonal to v?

Possible Answers:

\displaystyle -5\mathbf{i}+2\mathbf{j}+3\mathbf{k}

\displaystyle -\mathbf{i}+3\mathbf{k}

\displaystyle 4\mathbf{i}-2\mathbf{j}+\mathbf{k}

\displaystyle -4\mathbf{i}+3\mathbf{j}-2\mathbf{k}

\displaystyle 6\mathbf{i}+-3\mathbf{j}+5\mathbf{k}

Correct answer:

\displaystyle 4\mathbf{i}-2\mathbf{j}+\mathbf{k}

Explanation:

Two vectors are defined as orthogonal when their dot product is zero.

 

The dot product of two vectors

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

Is given by the expression:

\displaystyle \mathbf{u}\cdot\mathbf{v}=u_xv_x+u_yv_y+u_zv_z

 

The only vector that satisfies the requirement that the dot product of it and is zero is \displaystyle 4\mathbf{i}-2\mathbf{j}+\mathbf{k}:

\displaystyle (3\mathbf{i}+7\mathbf{j}+2\mathbf{k})\cdot (4\mathbf{i}-2\mathbf{j}+\mathbf{k}) =(3)(4)+(7)(-2)+(2)(2)=12-14+2=0

Example Question #451 : Vectors And Vector Operations

Find the dot product between the vectors \displaystyle \left \langle 3x,y,5z\right \rangle and \displaystyle \left \langle x^2,y^3,z^4\right \rangle

Possible Answers:

\displaystyle 3x^3+y^4+5z^5

\displaystyle 3x+y+5z+x^2+y^3+z^4

\displaystyle x^3+y+z

\displaystyle 3x^2+y^3+z^4

Correct answer:

\displaystyle 3x^3+y^4+5z^5

Explanation:

To find the dot product between the 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, we use the formula

\displaystyle a\cdot b=(x_1*x_2)+(y_1*y_2)+(z_1*z_2). Using the vectors from the problem statement, we get

\displaystyle (3x*x^2)+(y*y^3)+(5z*z^4)=3x^3+y^4+5z^5

Example Question #132 : Dot Product

Find the dot product between the vectors \displaystyle \left \langle -4,-10,1\right \rangle and \displaystyle \left \langle x,y^2,z\right \rangle

Possible Answers:

\displaystyle -4x-10y^2+z

\displaystyle 4x^3-5y^2+z

\displaystyle 4-10y+z

\displaystyle 4x^2-10y^2+1

Correct answer:

\displaystyle -4x-10y^2+z

Explanation:

o find the dot product between the 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, we use the formula

\displaystyle a\cdot b=(x_1*x_2)+(y_1*y_2)+(z_1*z_2). Using the vectors from the problem statement, we get

\displaystyle (-4*x)+(-10*y^2)+(1*z)=-4x-10y^2+z

Example Question #2451 : Calculus 3

Solve:

\displaystyle \left \langle z, y^3z^2, x\right \rangle \cdot \left \langle 2, e^x, x\right \rangle

Possible Answers:

\displaystyle 2z+e^xy^3z^2+x

\displaystyle 2z+e^xy^3z^2+2x

\displaystyle \left \langle 2z, e^xy^3z^2, x^2 \right \rangle

\displaystyle 2z+e^xy^3z^2+x^2

Correct answer:

\displaystyle 2z+e^xy^3z^2+x^2

Explanation:

The dot product of two vectors is given by the sum of the products of the corresponding components (for example, \displaystyle \left \langle a, b\right \rangle \cdot \left \langle c, d\right \rangle=ac+bd)

Our final answer is

\displaystyle 2z+e^xy^3z^2+x^2

Example Question #453 : Vectors And Vector Operations

Find the dot product between the vectors \displaystyle \left \langle x,y,4z\right \rangle and \displaystyle \left \langle 3,-7,1\right \rangle

Possible Answers:

\displaystyle 2x-7y+4z

\displaystyle 3x-7y+4z

\displaystyle 3x-7y-z

\displaystyle 3x-y+4z

Correct answer:

\displaystyle 3x-7y+4z

Explanation:

To find the dot product between 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, we apply the formula:

\displaystyle a\cdot b=(x_1*x_2)+(y_1*y_2)+(z_1*z_2)

Using the vectors from the problem statement, we get

\displaystyle (x*3)+(y*-7)+(4z*1)=3x-7y+4z

Example Question #454 : Vectors And Vector Operations

Find the dot product between the vectors \displaystyle \left \langle 4,1,-5\right \rangle and \displaystyle \left \langle 2,-8,1\right \rangle

Possible Answers:

\displaystyle -5

\displaystyle 5

\displaystyle 17

\displaystyle -15

Correct answer:

\displaystyle -5

Explanation:

To find the dot product between 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, we apply the formula:

\displaystyle a\cdot b=(x_1*x_2)+(y_1*y_2)+(z_1*z_2)

Using the vectors from the problem statement, we get

\displaystyle (4*2)+(1*-8)+(-5*1)=-5

Example Question #455 : Vectors And Vector Operations

Find the dot product between the vectors \displaystyle \left \langle 3,0,-6\right \rangle and \displaystyle \left \langle 1,-2,3\right \rangle

Possible Answers:

\displaystyle 12

\displaystyle 11

\displaystyle -15

\displaystyle 15

Correct answer:

\displaystyle -15

Explanation:

To find the dot product between 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, you apply the following formula:

\displaystyle a\cdot b=(x_1*x_2)+(y_1*y_2)+(z_1*z_2). Applying to the vectors from the problem statement, we get:

\displaystyle (3*1)+(0*-2)+(-6*3)=-15

Example Question #456 : Vectors And Vector Operations

Find the dot product between the vectors \displaystyle \left \langle x^3,3,1\right \rangle and \displaystyle \left \langle 4x^3,-7,2\right \rangle

Possible Answers:

\displaystyle 4x^6-19

\displaystyle 7x-10

\displaystyle 3x^6-17

\displaystyle x^4-16

Correct answer:

\displaystyle 4x^6-19

Explanation:

To find the dot product between 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, you apply the following formula:

\displaystyle a\cdot b=(x_1*x_2)+(y_1*y_2)+(z_1*z_2). Applying to the vectors from the problem statement, we get:

\displaystyle (x^3*4x^3)+(3*-7)+(1*2)=4x^6-19

Example Question #141 : Dot Product

Find the dot product of the two vectors:

\displaystyle \left \langle 3, xz, yz^2\right \rangle \cdot \left \langle xy, xyz, z\right \rangle

Possible Answers:

\displaystyle 3xy+x^2yz^2+yz

\displaystyle 3xy+xyz^2+yz^3

\displaystyle 3xy+x^2yz^2+yz^3

\displaystyle \left \langle 3xy, x^2yz^2,yz^3 \right \rangle

Correct answer:

\displaystyle 3xy+x^2yz^2+yz^3

Explanation:

The dot product of two vectors is given by the sum of the products of the corresponding components (for example, \displaystyle \left \langle a,b\right \rangle \cdot \left \langle c,d\right \rangle = ac+bd)

Our final answer is

\displaystyle 3xy+x^2yz^2+yz^3

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