GRE Subject Test: Math : Vectors

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

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Example Questions

Example Question #71 : Linear Algebra

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

Possible Answers:

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

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

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

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

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

Correct answer:

\displaystyle \left \langle 1,0,-3\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-3k , we can derive the vector form \displaystyle \left \langle 1,0,-3\right \rangle.

Example Question #72 : Linear Algebra

What is the vector form of \displaystyle 2i-j?

Possible Answers:

\displaystyle \left \langle 2,1,0\right \rangle

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

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

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

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

Correct answer:

\displaystyle \left \langle 2,-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 2i-j , we can derive the vector form \displaystyle \left \langle 2,-1,0\right \rangle.

Example Question #241 : Algebra

Write the following parametric equation in vector form.

\displaystyle z=t^3s

\displaystyle x=0

\displaystyle y=s^2

Possible Answers:

\displaystyle \left< 0,s^2,t^3s\right>

\displaystyle \left< 0, s^2, x^3y\right>

\displaystyle \left< s^2, t^3s,0\right>

\displaystyle \left< 0,t^3s, s^2\right>

Correct answer:

\displaystyle \left< 0,s^2,t^3s\right>

Explanation:

When converting parametric equations to vector valued functions, remember that the order of vectors goes as follows.

\displaystyle < x-component, y-component, z-component>

Given the question

\displaystyle z=t^3s

\displaystyle x=0

\displaystyle y=s^2

the vector would be given as, 

\displaystyle \left< 0, s^2, t^3s\right>.

Example Question #71 : Linear Algebra

What is the vector form of \displaystyle 10i-9j+8k?

Possible Answers:

\displaystyle \left \langle -10,-9,-8\right \rangle

\displaystyle \left \langle 10,-9,8\right \rangle

\displaystyle \left \langle 10,9,-8\right \rangle

\displaystyle \left \langle -10,9,8\right \rangle

\displaystyle \left \langle -10,9,-8\right \rangle

Correct answer:

\displaystyle \left \langle 10,-9,8\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-9j+8k, we can derive the vector form \displaystyle \left \langle 10,-9,8\right \rangle

Example Question #53 : Vectors & Spaces

What is the vector form of \displaystyle 4i+k?

Possible Answers:

\displaystyle \left \langle 0,4,1\right \rangle

\displaystyle \left \langle 4,0,1\right \rangle

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

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

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

Correct answer:

\displaystyle \left \langle 4,0,1\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 4i+k, we can derive the vector form \displaystyle \left \langle 4,0,1\right \rangle

Example Question #73 : Linear Algebra

What is the vector form of \displaystyle 2i-3j?

Possible Answers:

\displaystyle \left \langle 0,2,-3\right \rangle

\displaystyle \left \langle 2,3,0\right \rangle

\displaystyle \left \langle- 2,3,0\right \rangle

\displaystyle \left \langle- 2,-3,0\right \rangle

\displaystyle \left \langle 2,-3,0\right \rangle

Correct answer:

\displaystyle \left \langle 2,-3,0\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 2i-3j, we can derive the vector form \displaystyle \left \langle 2,-3,0\right \rangle

Example Question #51 : Vectors

Find the vector in standard form if the initial point is located at \displaystyle (3,7) and the terminal point is located at \displaystyle (7,10).

Possible Answers:

\displaystyle -4i-3j

\displaystyle 4i+3j

\displaystyle 7i+3j

\displaystyle i+j

Correct answer:

\displaystyle 4i+3j

Explanation:

We must first find the vector in component form.

If the initial point is \displaystyle (p_1,p_2) and the terminal point is \displaystyle (q_1,q_2) then the component form of the vector is \displaystyle \left< q_1-p_1,q_2-p_2\right>.

As such, the component form of the vector in the problem is \displaystyle \left< 7-3,10-7\right> \displaystyle =\left< 4,3\right>

Next, any vector with component form \displaystyle \left< a,b\right> can be written in standard form as  \displaystyle ai+bj .

Hence, the vector in standard form is

\displaystyle 4i+3j

Example Question #52 : Vector Form

What is the vector form of \displaystyle 3i-5j+7k?

Possible Answers:

\displaystyle \left \langle 3,-5,7\right \rangle

\displaystyle \left \langle -3,-5,-7\right \rangle

\displaystyle \left \langle -3,-5,7\right \rangle

\displaystyle \left \langle 3,5,-7\right \rangle

\displaystyle \left \langle -3,5,7\right \rangle

Correct answer:

\displaystyle \left \langle 3,-5,7\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 \displaystyle a=\left \langle a_{1},a_{2},a_{3}\right \rangle.

So for \displaystyle 3i-5j+7k, we can derive the vector form \displaystyle \left \langle 3,-5,7\right \rangle.

Example Question #432 : Gre Subject Test: Math

What is the vector form of \displaystyle 7i?

Possible Answers:

\displaystyle \left \langle 0,0,7\right \rangle

\displaystyle \left \langle -7,0,0\right \rangle

\displaystyle \left \langle 0,0,-7\right \rangle

\displaystyle \left \langle 7,0,0\right \rangle

\displaystyle \left \langle 0,7,0,\right \rangle

Correct answer:

\displaystyle \left \langle 7,0,0\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 7i, we can derive the vector form \displaystyle \left \langle 7,0,0\right \rangle.

Example Question #401 : Parametric, Polar, And Vector

Given points and , what is the vector form of the distance between the points?

Possible Answers:

\displaystyle \left \langle -4,2,8\right \rangle

\displaystyle \left \langle 4,-2,8\right \rangle

\displaystyle \left \langle -4,-2,-8\right \rangle

\displaystyle \left \langle 4,2,8\right \rangle

\displaystyle \left \langle -4,-2,8\right \rangle

Correct answer:

\displaystyle \left \langle -4,-2,8\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 \displaystyle b=\left \langle b_1,b_2,b_3\right \rangle,

the distance is the vector 

\displaystyle v=\left \langle b_1-a_1,b_2-a_2,b_3-a_3\right \rangle

Subbing in our original points  and ,  we get:

\displaystyle v=\left \langle 5-9,2-4,7-(-1)\right \rangle

\displaystyle v=\left \langle -4,-2,8\right \rangle

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