Calculus 3 : Vector Subtraction

Study concepts, example questions & explanations for Calculus 3

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Example Questions

Example Question #282 : Vectors And Vector Operations

Find the difference \(\displaystyle u-v\)

\(\displaystyle u=< 2,3>\)

\(\displaystyle v=< 0,1>\)

Possible Answers:

\(\displaystyle < -2,-2>\)

\(\displaystyle < 2,4>\)

\(\displaystyle 4\)

\(\displaystyle < 2,2>\)

Correct answer:

\(\displaystyle < 2,2>\)

Explanation:

The difference \(\displaystyle a-b\) of two vectors \(\displaystyle < a_1,a_2>\) and \(\displaystyle < b_1,b_2>\) is defined as

\(\displaystyle < a_1-b_1,a_2-b_2>\)

For the two vectors 

\(\displaystyle u=< 2,3>\)

\(\displaystyle v=< 0,1>\)

The difference is

\(\displaystyle u-v=< 2,3>-< 0,1>\)

\(\displaystyle =< 2-0,3-1>\)

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

Example Question #1 : Vector Subtraction

Given the vectors

\(\displaystyle v=(1,3)\)

\(\displaystyle w=(5,2)\)

find \(\displaystyle v-w\).

Possible Answers:

\(\displaystyle v-w=(1,-4)\)

\(\displaystyle v-w=(-4,1)\)

\(\displaystyle v-w=(4,-1)\)

\(\displaystyle v-w=(6,5)\)

Correct answer:

\(\displaystyle v-w=(-4,1)\)

Explanation:

Given the vectors

\(\displaystyle v=(1,3)\)

\(\displaystyle w=(5,2)\)

we can find the difference \(\displaystyle v-w\) by subtracting component-wise

\(\displaystyle v-w=(1,3)-(5,2)=(1-5,3-2)=(-4,1)\)

Example Question #3 : Vector Subtraction

Perform the following operation on the vectors specified below:

\(\displaystyle 3\mathbf{u}-2\mathbf{v}\)

Where

\(\displaystyle \mathbf{u}=4 \mathbf{i}+8\mathbf{j}+12\mathbf{k},\: \mathbf{v}=3\mathbf{i}+6\mathbf{j}+9\mathbf{k}\)

Possible Answers:

\(\displaystyle 6\mathbf{i}+12\mathbf{j}+18\mathbf{k}\)

\(\displaystyle 17\mathbf{i}+34\mathbf{j}+51\mathbf{k}\)

\(\displaystyle 7\mathbf{i}+12\mathbf{j}+17\mathbf{k}\)

\(\displaystyle \mathbf{i}+2\mathbf{j}+3\mathbf{k}\)

\(\displaystyle 18\mathbf{i}+36\mathbf{j}+54\mathbf{k}\)

Correct answer:

\(\displaystyle 6\mathbf{i}+12\mathbf{j}+18\mathbf{k}\)

Explanation:

First, multiply out the vectors by their corresponding coefficients:

\(\displaystyle 3\mathbf{u}=3(4\mathbf{i}+8\mathbf{j}+12\mathbf{k})=12\mathbf{i}+24\mathbf{j}+36\mathbf{k}\)

\(\displaystyle 2\mathbf{v}=2(3\mathbf{i}+6\mathbf{j}+9\mathbf{k})=6\mathbf{i}+12\mathbf{j}+18\mathbf{k}\)

Now we simply subtract the two vectors:

\(\displaystyle 3\mathbf{u}-2\mathbf{v}=(12-6)\mathbf{i}+(24-12)\mathbf{j}+(36-18)\mathbf{k}=6\mathbf{i}+12\mathbf{j}+18\mathbf{k}\)

Example Question #1 : Vector Subtraction

Subtract the vectors \(\displaystyle \left \langle -3,6,-9\right \rangle\) and \(\displaystyle \left \langle -1,2,-9\right \rangle\)

Possible Answers:

\(\displaystyle \left \langle -2,4,-18\right \rangle\)

\(\displaystyle \left \langle -2,4,0\right \rangle\)

\(\displaystyle \left \langle -4,8,-18\right \rangle\)

\(\displaystyle \left \langle -2,0,4\right \rangle\)

\(\displaystyle \left \langle -4,4,-18\right \rangle\)

Correct answer:

\(\displaystyle \left \langle -2,4,0\right \rangle\)

Explanation:

Set up an expression to subtract the vectors.

\(\displaystyle \left \langle -3,6,-9\right \rangle-\left \langle -1,2,-9\right \rangle\)

Be sure to make note of the sign change when subtracting the vectors.

\(\displaystyle \left \langle -3-(-1),6-2,(-9)-(-9)\right \rangle\)

Simplify the vector.

The answer is:  \(\displaystyle \left \langle -2,4,0\right \rangle\)

Example Question #5 : Vector Subtraction

Find the difference, \(\displaystyle u-v\), of the two vectors.
\(\displaystyle u=< -3,-7>\)
\(\displaystyle v=< 6,4>\)

Possible Answers:

\(\displaystyle < -9,-11>\)

\(\displaystyle < 3,-3>\)

\(\displaystyle < -3,3>\)

\(\displaystyle < 9,11>\)

Correct answer:

\(\displaystyle < -9,-11>\)

Explanation:

To find the difference, \(\displaystyle u-v\), we distribute the minus sign and turn it into vector addition.
\(\displaystyle u-v=< -3,-7>-< 6,4>=< -3,-7>+< -6,-4>\)
The sum of two vectors is defined as

The sum of two vectors 

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

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

is defined as 

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

As such, the difference is

\(\displaystyle < -9,-11>\)

Example Question #1 : Vector Subtraction

Compute the following: \(\displaystyle \left \langle 1,3,2\right \rangle-\left \langle 2,-4,1\right \rangle\).

Possible Answers:

\(\displaystyle \left \langle -1,7,1\right \rangle\)

\(\displaystyle \left \langle 3,-7,2\right \rangle\)

\(\displaystyle \left \langle -1,1,1\right \rangle\)

\(\displaystyle \left \langle -2,0,1\right \rangle\)

Correct answer:

\(\displaystyle \left \langle -1,7,1\right \rangle\)

Explanation:

The formula for subtracting vectors is \(\displaystyle a-b=\left \langle a_1-b_!,a_2-b_2,a_3-b_3\right \rangle\). Plugging in the values we were given, we get \(\displaystyle \left \langle (1-2),(3--4),(2-1)\right \rangle=\left \langle -1,7,1\right \rangle\)

Example Question #2 : Vector Subtraction

Solve:

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

Possible Answers:

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

\(\displaystyle \left \langle z-\ln(z), 0, y^2z-2\right \rangle\)

\(\displaystyle \left \langle z-\ln(z), 1, y^2z-2\right \rangle\)

\(\displaystyle z-\ln(z)+y^2z-2\)

Correct answer:

\(\displaystyle \left \langle z-\ln(z), 0, y^2z-2\right \rangle\)

Explanation:

To subtract vectors, we simply subtract their respective components:

\(\displaystyle \left \langle z-\ln(z), 0, y^2z-2\right \rangle\)

Note that our result is a vector still.

Example Question #293 : Vectors And Vector Operations

Find the difference between \(\displaystyle \left \langle 2,0,6\right \rangle\) and \(\displaystyle \left \langle 3,3,1\right \rangle\).

Possible Answers:

\(\displaystyle \left \langle 2,0,5\right \rangle\)

\(\displaystyle \left \langle 0,-1,4\right \rangle\)

\(\displaystyle \left \langle -1,-3,5\right \rangle\)

\(\displaystyle \left \langle 1,3,1\right \rangle\)

Correct answer:

\(\displaystyle \left \langle -1,-3,5\right \rangle\)

Explanation:

The formula for the difference of vectors is 

\(\displaystyle \left \langle x_1,x_2,x_3\right \rangle-\left \langle y_1,y_2,y_3\right \rangle=\left \langle x_1-y_1,x_2-y_2,x_3-y_3\right \rangle\)

Using the vectors given, we get 

\(\displaystyle \left \langle 2-3,0-3,6-1\right \rangle=\left \langle -1,-3,5\right \rangle\).

 

Example Question #3 : Vector Subtraction

Compute the following operation: \(\displaystyle \left \langle 2,5,19\right \rangle-\left \langle 3,0,1\right \rangle\).

Possible Answers:

\(\displaystyle \left \langle 2,0,0\right \rangle\)

\(\displaystyle \left \langle -2,6,10\right \rangle\)

\(\displaystyle \left \langle -1,5,18\right \rangle\)

\(\displaystyle \left \langle 17,38,12\right \rangle\)

Correct answer:

\(\displaystyle \left \langle -1,5,18\right \rangle\)

Explanation:

The formula for subtracting vectors a and b is 

\(\displaystyle a-b=\left \langle a_1-b_1,a_2-b_2,a_3-b_3\right \rangle\).

Plugging in the values we were given, we get 

\(\displaystyle \left \langle (2-3),(5-0),(19-1)\right \rangle=\left \langle -1,5,18\right \rangle\)

Example Question #4 : Vector Subtraction

Perform the following vector operation: \(\displaystyle \left \langle 2,12,13\right \rangle-\left \langle 5,5,1\right \rangle\)

Possible Answers:

\(\displaystyle 16\)

\(\displaystyle \left \langle 3,7,12\right \rangle\)

\(\displaystyle \left \langle -2,1,5\right \rangle\)

\(\displaystyle \left \langle -3,7,12\right \rangle\)

Correct answer:

\(\displaystyle \left \langle -3,7,12\right \rangle\)

Explanation:

The formula for the difference of 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, we get \(\displaystyle \left \langle (2-5),(12-5),(13-1) \right \rangle=\left \langle -3,7,12\right \rangle\)

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