GRE Subject Test: Math : Linear Algebra

Study concepts, example questions & explanations for GRE Subject Test: Math

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Example Questions

Example Question #434 : Parametric, Polar, And Vector

What is the vector form of \(\displaystyle 10i-j+10k\)?

Possible Answers:

\(\displaystyle \left \langle 10,1,10\right \rangle\)

\(\displaystyle \left \langle -1,10,10\right \rangle\)

\(\displaystyle \left \langle 10,10,1\right \rangle\)

\(\displaystyle \left \langle 10,-1,10\right \rangle\)

\(\displaystyle \left \langle 10,10,-1\right \rangle\)

Correct answer:

\(\displaystyle \left \langle 10,-1,10\right \rangle\)

Explanation:

In order to derive the vector form, we must map the , , -coordinates to their corresponding , , and coefficients.

That is, given , the vector form is  .

So for \(\displaystyle 10i-j+10k\) , we can derive the vector form \(\displaystyle \left \langle 10,-1,10\right \rangle\).

 

Example Question #84 : Vector

What is the vector form of \(\displaystyle i+j\)?

Possible Answers:

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

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

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

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

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

Correct answer:

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

Explanation:

In order to derive the vector form, we must map the -coordinates to their corresponding , and  coefficients.

That is, given, the vector form is  .

So for \(\displaystyle i+j\) , we can derive the vector form \(\displaystyle \left \langle 1,1,0\right \rangle\).

Example Question #91 : Vectors

Given points \(\displaystyle (0,8,-1)\) and \(\displaystyle (2,2,2)\), what is the vector form of the distance between the points?

 

Possible Answers:

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

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

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

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

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

Correct answer:

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

Explanation:

In order to derive the vector form of the distance between two points, we must find the difference between the , , and elements of the points.

That is, for any point and , the distance is the vector .

Subbing in our original points \(\displaystyle (0,8,-1)\) and \(\displaystyle (2,2,2)\), we get:

\(\displaystyle v=\left \langle 2-0,2-8,2-(-1)\right \rangle\)

\(\displaystyle v=\left \langle 2,-6,3\right \rangle\)

 

Example Question #91 : Vector Form

What is the vector form of \(\displaystyle -6i+j+k\)?

Possible Answers:

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

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

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

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

\(\displaystyle \left \langle 6,1,1\right \rangle\)

Correct answer:

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

Explanation:

In order to derive the vector form, we must map the , , -coordinates to their corresponding , , and coefficients.

That is, given, the vector form is  .

So for \(\displaystyle -6i+j+k\), we can derive the vector form \(\displaystyle \left \langle -6,1,1\right \rangle\).

Example Question #91 : Vector Form

What is the vector form of \(\displaystyle 3i-k\)?

Possible Answers:

\(\displaystyle \left \langle 3,0,-1\right \rangle\)

\(\displaystyle \left \langle 3,-1,0\right \rangle\)

\(\displaystyle \left \langle -3,0,-1\right \rangle\)

\(\displaystyle \left \langle 3,0,1\right \rangle\)

\(\displaystyle \left \langle -3,0,1\right \rangle\)

Correct answer:

\(\displaystyle \left \langle 3,0,-1\right \rangle\)

Explanation:

In order to derive the vector form, we must map the -coordinates to their corresponding , and coefficients.

That is, given, the vector form is  .

So for \(\displaystyle 3i-k\), we can derive the vector form \(\displaystyle \left \langle 3,0,-1\right \rangle\).

Example Question #1 : Vector Form

Given points \(\displaystyle (4,2,-2)\) and \(\displaystyle (7,1,0)\), what is the vector form of the distance between the points?

Possible Answers:

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

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

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

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

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

Correct answer:

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

Explanation:

In order to derive the vector form of the distance between two points, we must find the difference between the , , and elements of the points.

That is, for any point and , the distance is the vector .

Subbing in our original points \(\displaystyle (4,2,-2)\) and \(\displaystyle (7,1,0)\),  we get:

\(\displaystyle v=\left \langle 7-4,1-2,0-(-2)\right \rangle\)

\(\displaystyle v=\left \langle 3,-1,2\right \rangle\)

Example Question #91 : Vector Form

Given points \(\displaystyle (2,7,-6)\) and \(\displaystyle (1,2,3)\), what is the vector form of the distance between the points?

 

Possible Answers:

\(\displaystyle \left \langle 1,-5,-9\right \rangle\)

\(\displaystyle \left \langle -1,5,-9\right \rangle\)

\(\displaystyle \left \langle -1,-5,-9\right \rangle\)

\(\displaystyle \left \langle -1,-5,9\right \rangle\)

\(\displaystyle \left \langle 1,5,9\right \rangle\)

Correct answer:

\(\displaystyle \left \langle -1,-5,9\right \rangle\)

Explanation:

In order to derive the vector form of the distance between two points, we must find the difference between the , , and elements of the points.

That is, for any point and , the distance is the vector .

Subbing in our original points \(\displaystyle (2,7,-6)\) and \(\displaystyle (1,2,3)\),  we get:

 \(\displaystyle v=\left \langle 1-2,2-7,3-(-6)\right \rangle\)

\(\displaystyle v=\left \langle -1,-5,9\right \rangle\)

Example Question #441 : Parametric, Polar, And Vector

What is the vector form of \(\displaystyle -i+2j+10k\)?

Possible Answers:

\(\displaystyle \left \langle 1,2,-10\right \rangle\)

\(\displaystyle \left \langle 1,2,10\right \rangle\)

\(\displaystyle \left \langle -1,2,10\right \rangle\)

\(\displaystyle \left \langle 1,-2,-10\right \rangle\)

\(\displaystyle \left \langle 1,-2,10\right \rangle\)

Correct answer:

\(\displaystyle \left \langle -1,2,10\right \rangle\)

Explanation:

In order to derive the vector form, we must map the , , -coordinates to their corresponding , , and coefficients.

That is, given, the vector form is .

So for \(\displaystyle -i+2j+10k\), we can derive the vector form \(\displaystyle \left \langle -1,2,10\right \rangle\).

Example Question #92 : Vector Form

What is the vector form of \(\displaystyle i+k\)?

Possible Answers:

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

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

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

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

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

Correct answer:

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

Explanation:

In order to derive the vector form, we must map the -coordinates to their corresponding , and  coefficients.

That is, given , the vector form is .

So for \(\displaystyle i+k\), we can derive the vector form \(\displaystyle \left \langle 1,0,1\right \rangle\).

Example Question #91 : Vectors & Spaces

Calculate the dot product of the following vectors:  

\(\displaystyle a=\left \langle c,6, s\right \rangle\) 

\(\displaystyle b=\left \langle c,10,s\right \rangle\)

Possible Answers:

\(\displaystyle 60c^2s^2\)

\(\displaystyle c^2+60+s^2\)

\(\displaystyle 2cs+60\)

\(\displaystyle 2c+16+2s\)

\(\displaystyle c^2+16+s^2\)

Correct answer:

\(\displaystyle c^2+60+s^2\)

Explanation:

Write the formula for dot product given \(\displaystyle a=\left \langle a_{1},a_{2},a_{3}\right \rangle\) and \(\displaystyle b=\left \langle b_{1},b_{2},b_{3}\right \rangle\).

\(\displaystyle a\cdot b= a_{1}b_{1}+a_{2}b_{2}+a_{3}b_{3}\)

Substitute the values of the vectors to determine the dot product.

\(\displaystyle a\cdot b= c(c)+(6)(10)+s(s) = c^2+60+s^2\)

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