Khan Academy is an American non-profit educational organization created in 2006 by Sal Khan, with the goal of creating a set of online tools that help educate students. The organization produces short lessons in the form of videos. Its website also includes supplementary practice exercises and materials for educators. All resources are available for free to users of the website and application.

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1. ### Help Me Solve This Khan Academy Question: Friction and Initial Velocity

Here's a picture of the question: This is a Khan Academy question and although I could just click on hint to find out what the answer is, I think it would be helpful to still ask this here before looking at the answer over there, so that I know what I did wrong. Thank you in advance to anyone...
2. ### Foundations Textbooks vs Khan Academy for Self Study and PreCalc CLEP

Hi PF, I hope y'all had a great Thanksgiving. Quick question, as I've mentioned before, I am non-traditional college student who is right at just over College Algebra/beginning Trig level in Math. While I am out of university, to make enough money to return, I am wanting to CLEP...
3. ### Conservation of angular momentum

Homework Statement A rod of length D sits at rest on a friction less table. A ball of mass M strikes the end of the rod with a speed V and rebounds with a speed 3v/4 causing the rod to rotate counterclockwise around a fixed axis at one end. The rotational inertia of the rod is I Homework...

Hello, PhysicsForums. Right now, I am studying high school mathematics on Khan Academy, and it is working out great! I also read all of the articles and do the excersizes and I write down everything that I see. I feel that I will achieve mastery of Algebra, Geometry, and Trigonometry in no time...
5. ### MHB Sal Khan Founder of Khan Academy

I am confused. A man named Sal Khan founded the Khan Academy to help struggling students around the globe academically online. Sal had a job making over \$100,000 a year and decided to quit his job to teach math online for free. Question: Is Sal a genius? Why is it that certain people in life...
6. ### What are variables, expressions, and equations? | Introduction to algebra | Algebra I | Khan Academy

Learn what variables, expressions, and equations really are. Practice this lesson yourself on KhanAcademy.org right now: https://www.khanacademy.org/math/alg...
7. ### How to test solutions to equations using substitution | 6th grade | Khan Academy

A solution to an equation makes that equation true. Learn how to test if a certain value of a variable makes an equation true. Practice this lesson yourself ...
8. ### Why we do the same thing to both sides of equations | Linear equations | Algebra I | Khan Academy

The example of a scale where we try to achieve balance helps to explain why we do the same thing to both sides of an equation. Practice this lesson yourself ...
9. ### How to represent a relationship with a simple equation | Linear equations | Algebra I | Khan Academy

Equations are about relationships (no, not girlfriends and boyfriends!) between the two sides of the equation. Let's again use a scale example to help us und...
10. ### Intuition for solving one-step equations | Linear equations | Algebra I | Khan Academy

This equation can be simplified through a single step to solve for the variable. Can you help? Practice this lesson yourself on KhanAcademy.org right now: ht...
11. ### How to divide from both sides of an equation | Linear equations | Algebra I | Khan Academy

Let's get a conceptual understanding of why one needs to divide both sides of an equation to solve for a variable. Watch the next lesson: https://www.khanaca...
12. ### How to solve one-step equations | Linear equations | Algebra I | Khan Academy

Learn how to solve one-step addition and subtraction equations by adding or subtracting the same thing from both sides of the equation. Watch the next lesson...
13. ### Example of solving a one-step equation | Linear equations | Algebra I | Khan Academy

Learn how to solve this equation: a + 5 = 54 Practice this lesson yourself on KhanAcademy.org right now: https://www.khanacademy.org/math/algebra/solving-lin...
14. ### How to solve one-step equations with fractions and decimals | 6th grade | Khan Academy

Learn how to solve one-step addition and subtraction equations that have fractions and decimals in them. Practice this lesson yourself on KhanAcademy.org rig...
15. ### How to solve equations of the form ax = b | Linear equations | Algebra I | Khan Academy

Let's ease into this, shall we? Here's an introduction to basic algebraic equations of the form ax=b. Remember that you can check to see if you have the righ...
16. ### How to solve equations of the form x/a = b | Linear equations | Algebra I | Khan Academy

Remember that what you do to one side, you have to do to the other. Will you multiply or divide both sides to dump the fraction, x/a? Let's do it together. P...
17. ### How to solve one-step multiplication and division equations with fractions and decimals

"Learn how to solve equations in one step by multiplying or dividing a number from both sides. These problems involve decimals and fractions. Practice this l...
18. ### Solving two-step equations | Linear equations | Algebra I | Khan Academy

Here's how we solve a two step equation. It begins with the concept of equality: what we do to one side of the equation must be done to the other. Watch the ...
19. ### Solving a more complicated equation | Linear equations | Algebra I | Khan Academy

This example demonstrates how we solve an equation expressed such: ax + b = c. It's a little more complicated than previous examples, but you can do it! Prac...
20. ### Example: two-step equation with numerator x | Linear equations | Algebra I | Khan Academy

Solve the equation by isolating the term with numerator x. Practice this lesson yourself on KhanAcademy.org right now: https://www.khanacademy.org/math/algeb...
21. ### Basic linear equation word problem | 7th grade | Khan Academy

"Learn how to construct and solve a basic linear equation to solve a word problem. Practice this lesson yourself on KhanAcademy.org right now: https://www.kh...
22. ### Word problem: solving equations | Linear equations | Algebra I | Khan Academy

Here's a nifty word problem in which we find the dimensions of a garden given only the perimeter. Let's create an equation to solve! Practice this lesson you...
23. ### Linear equation word problem | Linear equations | Algebra I | Khan Academy

Learn how to solve a word problem by writing an equation to model the situation. In this video, we use the linear equation 210(t-5) = 41,790. Practice this l...

25. ### Introduction to solving an equation with variables on both sides | Algebra I | Khan Academy

Sal solves the equation 2x + 3 = 5x - 2. Practice this lesson yourself on KhanAcademy.org right now: https://www.khanacademy.org/math/algebra/solving-linear-...
26. ### Example 2: Variables on both sides | Linear equations | Algebra I | Khan Academy

Solving Equations 2 Practice this lesson yourself on KhanAcademy.org right now: https://www.khanacademy.org/math/algebra/solving-linear-equations-and-inequal...
27. ### A clever application of the distributive property to solve a multi-step equation | Khan Academy

Sal solves the equation (3/4)x + 2 = (3/8)x - 4 using the distributive property Practice this lesson yourself on KhanAcademy.org right now: https://www.khana...
28. ### Ex 2: Multi-step equation | Linear equations | Algebra I | Khan Academy

Turning a non-linear equation into a linear one. Watch the next lesson: https://www.khanacademy.org/math/algebra/solving-linear-equations-and-inequalities/co...
29. ### Solving equations with the distributive property | Linear equations | Algebra I | Khan Academy

Solving Equations with the Distributive Property Practice this lesson yourself on KhanAcademy.org right now: https://www.khanacademy.org/math/algebra/solving...
30. ### Number of solutions to linear equations | Linear equations | Algebra I | Khan Academy

Equation Special Cases Practice this lesson yourself on KhanAcademy.org right now: https://www.khanacademy.org/math/algebra/solving-linear-equations-and-ineq...
31. ### Equation special cases | Linear equations | Algebra I | Khan Academy

Equation Special Cases Watch the next lesson: https://www.khanacademy.org/math/algebra/solving-linear-equations-and-inequalities/solutions-linear-equations/v...

34. ### Solving a consecutive integer problem algebraically | Linear equations | Algebra I | Khan Academy - YouTube

The sum of 4 consecutive odd integers is 136. What are the 4 integers? Practice this lesson yourself on KhanAcademy.org right now: https://www.khanacademy.or...
35. ### Challenge example: Sum of integers | Linear equations | Algebra I | Khan Academy

Sum of Consecutive Odd Integers Practice this lesson yourself on KhanAcademy.org right now: https://www.khanacademy.org/math/algebra/solving-linear-equations...
36. ### Mixture problems 2 | Linear equations | Algebra I | Khan Academy

Mixture problems 2 Watch the next lesson: https://www.khanacademy.org/math/algebra/solving-linear-equations-and-inequalities/More-equation-practice/v/basic-r...
37. ### Mixture problems 3 | Linear equations | Algebra I | Khan Academy

Mixture problems 3 Watch the next lesson: https://www.khanacademy.org/math/algebra/solving-linear-equations-and-inequalities/old-school-equations/v/order-of-...
38. ### Linear equations with unknown coefficients

Linear equations with unknown coefficients
39. ### Abstract-ness | Introduction to algebra | Algebra I | Khan Academy

The general idea behind the word 'abstract' Watch the next lesson: https://www.khanacademy.org/math/algebra/introduction-to-algebra/overview_hist_alg/v/the-b...
40. ### The beauty of algebra | Introduction to algebra | Algebra I | Khan Academy

Why the abstraction of mathematics is so fundamental Watch the next lesson: https://www.khanacademy.org/math/algebra/introduction-to-algebra/overview_hist_al...
41. ### Introduction to the coordinate plane | Introduction to algebra | Algebra I | Khan Academy

Bridging algebra and geometry. What makes linear equations so linear. Watch the next lesson: https://www.khanacademy.org/math/algebra/introduction-to-algebra...
42. ### Why all the letters in algebra? | Introduction to algebra | Algebra I | Khan Academy

Jesse Roe and Sal Khan talk about why we use letters in algebra Watch the next lesson: https://www.khanacademy.org/math/algebra/introduction-to-algebra/varia...
43. ### What is a variable? | Introduction to algebra | Algebra I | Khan Academy

Our focus here is understanding that a variable is just a symbol that can represent different values in an expression. We got this. Just watch. Watch the nex...
44. ### Why aren't we using the multiplication sign? | Introduction to algebra | Algebra I | Khan Academy

Great question. In algebra, we do indeed avoid using the multiplication sign. We'll explain it for you here. Watch the next lesson: https://www.khanacademy.o...
45. ### How to evaluate an expression with variables | Introduction to algebra | Algebra I | Khan Academy

Learn how to evaluate an expression with variables using a technique called substitution (or "plugging in"). Watch the next lesson: https://www.khanacademy.o...
46. ### How to evaluate expressions with two variables | 6th grade | Khan Academy

We've done a few examples together where we were faced with 1 variable. Why not try one that has 2 variables? Practice this lesson yourself on KhanAcademy.or...
47. ### How to evaluate expressions in two variables with decimals and fractions | 6th grade | Khan Academy

Learn how to evaluate expressions that have two different variables in them by using a technique called substitution (or "plugging in"). Practice this lesson...
48. ### How to evaluate an expression using substitution | Algebra I | Khan Academy

In this example we have a formula for converting Celsius temperature to Fahrenheit. Let's substitute the variable with a value (Celsius temp) to get the degr...
49. ### Evaluating an algebraic expression in a word problem | Algebra I | Khan Academy

In this example of evaluating expressions, we're dusting off some geometry. On top of that, it's a word problem. We're seeing how different concepts in math ...
50. ### Evaluating an algebraic expression with exponents | 6th grade | Khan Academy

We're going to put our order of operations knowledge to work as we evaluate this expression. Exponents, specifically, are our focus here. Watch the next less...