Look inside "The Ultimate Crash Course"

Lesson 0: Technology that is Acceptable in a PLEM Degree
Lock Upgrade
Jun 23, 2025

Lesson 0: Technology that is Acceptable in a PLEM Degree

Show f(t) = t has laplace F(s) = 1/s^2
Lock Upgrade
Jun 22, 2025

Show f(t) = t has laplace F(s) = 1/s^2

Construct a Matrix with Given Column Space and Nullspace (Step-by-Step Proof) Construct a Matrix with Given Column Space and Nullspace (Step-by-Step Proof) Construct a Matrix with Given Column Space and Nullspace (Step-by-Step Proof)
Lock Upgrade
Jun 7, 2025

Construct a Matrix with Given Column Space and Nullspace (Step-by-Step Proof)

Title: Construct a Matrix with Given Column Space and Nullspace (Step-by-Step Proof)

In this walkthrough, we show how to construct a matrix whose column space contains (1,1,1) and whose nullspace is the line of multiples of (1,1,1,1).

Step 1: Understand the Problem

We want:

  • Column space to contain the vector (1,1,1)

  • Nullspace to be the set of all scalar multiples of (1,1,1,1)

This means we are looking for a matrix A such that:

  • A * x = 0 has solution space spanned by (1,1,1,1)

  • The matrix A has 3 rows (since the column vector has 3 entries)

  • The matrix A has 4 columns (since the nullspace vector has 4 components)

Step 2: Definitions

Column Space: All linear combinations of the columns
Nullspace: All solutions to A * x = 0
So x = t(1,1,1,1) is the general solution of the homogeneous system.

Step 3: Deconstruct and Solve

We assume:

x = (1,1,1,1)t
So, x₁ = x₂ = x₃ = x₄

This gives:

  • x₁ - x₂ = 0

  • x₂ - x₃ = 0

  • x₃ - x₄ = 0

Which gives us a system of equations:

x₁ - x₂ = 0  
x₂ - x₃ = 0  
x₃ - x₄ = 0

Written in matrix form:

[ 1 -1  0  0 ]  
[ 0  1 -1  0 ]  
[ 0  0  1 -1 ]

Thus, a correct matrix A is:

A = [ 1  0  0  -1  
      0  1  0  -1  
      0  0  1  -1 ]

This has:

  • Column space containing (1,1,1)

  • Nullspace spanned by (1,1,1,1)

Step 4: Validation

Any vector in the nullspace must satisfy A * x = 0.
Let x = (1,1,1,1), then:

A * x = [1 -1 0 0]·x = 1 - 1 = 0  
        [0 1 -1 0]·x = 1 - 1 = 0  
        [0 0 1 -1]·x = 1 - 1 = 0  

✅ Valid

And since (1,1,1) can be expressed as a linear combination of the columns, it's in the column space.

Conclusion

One valid matrix is:

A = [ 1  0  0  -1  
      0  1  0  -1  
      0  0  1  -1 ]

This matches the conditions exactly. There are infinitely many matrices that can satisfy these conditions, but this form is simplest and easily validated.

This lesson aligns with Chapter 3.2 in Strang’s Linear Algebra (4th ed.). Always cite sources and avoid shortcut tools like AI or uncredited platforms during exams unless explicitly allowed.

Visit:
https://author-jonathan-david-shop.fourthwall.com for more STEM guides.
Subscribe for live lessons and study advice: https://www.youtube.com/@AuthorJonD

Become a Member

Ultimate Crash Course Lessons & Podcast

Ultimate Crash Course Lessons & Podcast

$29.00 per month

This option gives full access to all video lessons by Author Jonathan David
  • Tick 800+ Video Lessons (and growing)
  • Tick 300+ Podcasts (and growing)
  • Tick Fiction eBooks [18+ Mature Audience]

Included with Membership: "i no i'm write" podcast

If you are a STEM Major, you really need to change your maturity now.
Lock Join to access
Sep 11, 2025

If you are a STEM Major, you really need to change your maturity now.

Practicing the Art of Being a Professional- How to speak to Professors in college
Lock Join to access
Sep 11, 2025

Practicing the Art of Being a Professional- How to speak to Professors in college

If you plan to use Khan Academy, my channel, or others like it, make sure you are aware of this
Lock Join to access
Sep 11, 2025

If you plan to use Khan Academy, my channel, or others like it, make sure you are aware of this

Physics: Electromagnetism

Lesson 1: The Most Important Part of an E&M Electromagnetism Textbook for University Physics Students
Lock Join to access
Aug 5, 2025

Lesson 1: The Most Important Part of an E&M Electromagnetism Textbook for University Physics Students

Excess Electrons on a Charged Sphere  Finding the Count  This video calculates the number of
Lock Join to access
Apr 16, 2025

Excess Electrons on a Charged Sphere Finding the Count This video calculates the number of

How to Read and Use | Introduction to Electrodynamics | by David J. Griffiths
Lock Join to access
Mar 27, 2025

How to Read and Use | Introduction to Electrodynamics | by David J. Griffiths

Physics: Mechanics

When writing by hand, just be neat and clear, as bold and italicization are not too easy by hand. When doing homework, you should be typing professional-looking documents, whereas when doing exams—that is, practice exams- you should practice by writing with pen or pencil and in a very unpleasant situation to mimic the real exam.  Take away: When it comes to units, students lose a lot of points for doing something like finalizing the answer by saying 10. Rather than 10.0 m/s. You will also have to account for significant figures. Meaning, 10 may be wrong and 10.0 is correct, but still wrong if not adding the units.  A physics student can do all the calculations correctly and still get a bad grade simply for sloppy notation. NASA would not hire someone who is not attentive to detail, nor would Apple, Google, or any other huge company that pays a lot of money for precision and accuracy!  As you begin your journey in physics, if you have not already restructured your way of thinking to be a professional, now is the time to do so!
Lock Join to access
Aug 6, 2025

When writing by hand, just be neat and clear, as bold and italicization are not too easy by hand. When doing homework, you should be typing professional-looking documents, whereas when doing exams—that is, practice exams- you should practice by writing with pen or pencil and in a very unpleasant situation to mimic the real exam. Take away: When it comes to units, students lose a lot of points for doing something like finalizing the answer by saying 10. Rather than 10.0 m/s. You will also have to account for significant figures. Meaning, 10 may be wrong and 10.0 is correct, but still wrong if not adding the units. A physics student can do all the calculations correctly and still get a bad grade simply for sloppy notation. NASA would not hire someone who is not attentive to detail, nor would Apple, Google, or any other huge company that pays a lot of money for precision and accuracy! As you begin your journey in physics, if you have not already restructured your way of thinking to be a professional, now is the time to do so!

Before Starting a College Physics Course | #1 | About this book
Lock Join to access
Jul 3, 2025

Before Starting a College Physics Course | #1 | About this book

A quick recap of some algebra topics needed for physics and review of the Before you Start Physics
Lock Join to access
May 1, 2025

A quick recap of some algebra topics needed for physics and review of the Before you Start Physics

Tips & Tricks for STEM

Sample Exam Question for Chain Rule in Calculus to Maximize Points
Lock Join to access
Sep 11, 2025

Sample Exam Question for Chain Rule in Calculus to Maximize Points

Algebra Solution Writing in Terms of Mathematical Essay for Point Maximization on Exams
Lock Join to access
Sep 11, 2025

Algebra Solution Writing in Terms of Mathematical Essay for Point Maximization on Exams

How to legally find textbooks via PDF form without pirating or torrenting
Lock Join to access
Aug 28, 2025

How to legally find textbooks via PDF form without pirating or torrenting

Advanced Topics

Lesson 7/ Index & Tensor Notation Intro to Cross Product Levi-Civita Notation
Lock Join to access
Sep 9, 2025

Lesson 7/ Index & Tensor Notation Intro to Cross Product Levi-Civita Notation

Lesson 5: Index & Tensor Notation - Indexing the Identity Matrix to Single and Double Sum
Lock Join to access
Sep 9, 2025

Lesson 5: Index & Tensor Notation - Indexing the Identity Matrix to Single and Double Sum

Lesson 3: Index and Tensor Notations: Intro to Kroneckor Delta Part 2- Dot Product vs. Innder Product
Lock Join to access
Sep 9, 2025

Lesson 3: Index and Tensor Notations: Intro to Kroneckor Delta Part 2- Dot Product vs. Innder Product

Linear Algebra

Introduction to Linear Algebra Notation
Lock Join to access
Aug 29, 2025

Introduction to Linear Algebra Notation

How to read a linear algebra textbook in college
Lock Join to access
Aug 29, 2025

How to read a linear algebra textbook in college

Comparing the David Lay, Gilbert Strang, and Jim Hefferon Textbooks for Linear Algebra
Lock Join to access
Aug 29, 2025

Comparing the David Lay, Gilbert Strang, and Jim Hefferon Textbooks for Linear Algebra

Differential Equations

Introduction to Differential Equations: Structuring Solutions for Exams and Homework
Lock Join to access
Aug 28, 2025

Introduction to Differential Equations: Structuring Solutions for Exams and Homework

Lesson 1/ Differential Equations- Wordpress, chatGPT and PDF textbooks - Some stuff for your resume
Lock Join to access
Aug 28, 2025

Lesson 1/ Differential Equations- Wordpress, chatGPT and PDF textbooks - Some stuff for your resume

Lesson 5: Separable Variable, Implicit Solution, General Solution, Particular Solution in Differential Equations
Lock Join to access
Aug 5, 2025

Lesson 5: Separable Variable, Implicit Solution, General Solution, Particular Solution in Differential Equations

Multivariable Calculus

1.1.2 The given equation involves a power of the variable. Find all real solutions of the equation.
Lock Join to access
Sep 13, 2025

1.1.2 The given equation involves a power of the variable. Find all real solutions of the equation.

1.1 Basic Equations   Determine whether the given value is a solution of the equation.
Lock Join to access
Sep 13, 2025

1.1 Basic Equations Determine whether the given value is a solution of the equation.

Find an equation of the set of all points equidistant from the points A(-1,5,3) and B(6,2,-2). Describe the set.
Lock Join to access
Sep 11, 2025

Find an equation of the set of all points equidistant from the points A(-1,5,3) and B(6,2,-2). Describe the set.

Integral Calculus

1.1.2 The given equation involves a power of the variable. Find all real solutions of the equation.
Lock Join to access
Sep 13, 2025

1.1.2 The given equation involves a power of the variable. Find all real solutions of the equation.

1.1 Basic Equations   Determine whether the given value is a solution of the equation.
Lock Join to access
Sep 13, 2025

1.1 Basic Equations Determine whether the given value is a solution of the equation.

Find an equation of the set of all points equidistant from the points A(-1,5,3) and B(6,2,-2). Describe the set.
Lock Join to access
Sep 11, 2025

Find an equation of the set of all points equidistant from the points A(-1,5,3) and B(6,2,-2). Describe the set.

Differential Calculus

Sample Exam Question for Chain Rule in Calculus to Maximize Points
Lock Join to access
Sep 11, 2025

Sample Exam Question for Chain Rule in Calculus to Maximize Points

Sample Exam Question for Calculus- The Chain Rule
Lock Join to access
Aug 19, 2025

Sample Exam Question for Calculus- The Chain Rule

The Algorithmic Approach to Taking Limits
Lock Join to access
Jul 8, 2025

The Algorithmic Approach to Taking Limits

Precalculus

1.1 - Real Numbers  Express the interval in terms of inequalities and then graph the interval.
Lock Join to access
Sep 11, 2025

1.1 - Real Numbers Express the interval in terms of inequalities and then graph the interval.

1.1 The Distance and Midpoint Formulas  Pythagorean Theorem/ Distance Formula
Lock Join to access
Aug 6, 2025

1.1 The Distance and Midpoint Formulas Pythagorean Theorem/ Distance Formula

1.1 The Distance and Midpoint Formulas  Pythagorean Theorem/ Distance Formula
Lock Join to access
Aug 6, 2025

1.1 The Distance and Midpoint Formulas Pythagorean Theorem/ Distance Formula

Trigonometry

A denotes the area of the sector of a circle of radius r formed by the central angle . Find the missing quantity. Round answers to three decimal places.
Lock Join to access
Sep 11, 2025

A denotes the area of the sector of a circle of radius r formed by the central angle . Find the missing quantity. Round answers to three decimal places.

Find all points having an x-coordinate of 3 whose distance from the point (-2,-1) is 13.  (a) By using the Pythagorean Theorem. (b) By using the distance formula.
Lock Join to access
Aug 6, 2025

Find all points having an x-coordinate of 3 whose distance from the point (-2,-1) is 13. (a) By using the Pythagorean Theorem. (b) By using the distance formula.

Lesson 2.6: Amplitude, Period, and Phase Shift  Find the amplitude, period, and phase shift of each function. Graph each function. Be sure to label key points. Show at least two periods.
Lock Join to access
Aug 3, 2025

Lesson 2.6: Amplitude, Period, and Phase Shift Find the amplitude, period, and phase shift of each function. Graph each function. Be sure to label key points. Show at least two periods.

College Algebra

1.1.2 The given equation involves a power of the variable. Find all real solutions of the equation.
Lock Join to access
Sep 13, 2025

1.1.2 The given equation involves a power of the variable. Find all real solutions of the equation.

1.1 Basic Equations   Determine whether the given value is a solution of the equation.
Lock Join to access
Sep 13, 2025

1.1 Basic Equations Determine whether the given value is a solution of the equation.

Chapter 1 – Equations and Inequalities
Lock Join to access
Sep 11, 2025

Chapter 1 – Equations and Inequalities