A home for the things you study

Learn one idea at a time, with spaced repetition flashcards and exams that show the working. Write your own courses in enhanced Markdown and keep them in git: the repository's address is the link you share.

Open the app Write a course

Card by card

Short cards, one idea each, with real equations and interactive graphs. Then flashcards with spaced repetition, and exams that show the working.
Write what you know

A course is a git repository of enhanced Markdown: a folder for each part, a file for each deck. Write it yourself, or have an AI draft it. How to write a course
Pass it on

The repository's address is the link. Anyone who opens it studies your course, and each push reaches them.
And beyond

Courses in mathematics and physics come with the app. No account needed, and it works offline.

Start studying

Open a course that comes with the app, or one that someone shared with you.

Open the app Write a course

Algebra 25%

Linear equationsSolving a linear equation

A linear equation in one unknown has the form $a x + b = 0$ . Solve it by isolating the unknown, undoing each operation in turn.

2 x + 4 = 10 ⟹ 2 x = 6 ⟹ x = 3

The graph of $y = a x + b$ is a straight line. The slope tilts it; it meets the vertical axis at its intercept. Drag the line and watch it turn.

Check every answer: put it back in. With $x = 3$ , $2 \cdot 3 + 4 = 10$ .

Linear equationsFlashcards1/6 answered

Start over

Concepts 4

The rest of the concept cards.

A rectangle is 3 m wide and has area $12 m^{2}$ . How long is it?

Solve $3 x - 6 = 9$ for $x$ .

$x = 5$ . Add 6, then divide by 3.

AgainAlmostPerfect

Where does $y = 2 x + 3$ meet the vertical axis?

A line has slope $0$ . What does its graph look like?

Due 2

Scheduled for today.

Solve $5 x = 2 x + 9$ .

What is the slope of $y = 4 - x$ ?

ExamsLinear equations1/3 read

Solve $4 x + 7 = 23$ .

Answer

$x = 4$ . Subtract 7 from both sides, then divide by 4.

A line has slope 3 and meets the vertical axis at 2. Write its equation.

Answer

$y = 3 x + 2$ . The slope is $a$ , and the intercept is $b$ .

Solve $2 (x - 1) = x + 5$ .

Answer

$x = 7$ . Expand to $2 x - 2$ , then bring every $x$ to one side.

2Writegit

alice/algebramain

├─ index.md
└─ algebra/
   ├─ index.md
   └─ equations/
      ├─ index.md
      ├─ linear/
      │  ├─ index.md
      │  └─ solving.md
      └─ quadratic/
         ├─ index.md
         └─ formula.md

algebra/equations/linear/solving.md

1---

2title: Solving a linear equation

3---

5::: card

6A *linear equation* in one unknown has the form $ax + b = 0$.

7Solve it by isolating the unknown, undoing each operation in turn.

9$$ 2x + 4 = 10 \implies 2x = 6 \implies x = 3 $$

10:::

12::: flashcard q1

13Solve $3x - 6 = 9$ for $x$.

15::: answer

16$x = 5$. Add 6, then divide by 3.

17:::

18:::

3Checkterminal

$ stemin check algebra

ERROR algebra/equations/quadratic/formula.md:21: this block has no ::: answer: a flashcard needs its back, and a question its answer

The fix:

21::: flashcard q2

22Solve $x^2 - 5x + 6 = 0$.

23::: answer

24$x = 2$ or $x = 3$. It factors as $(x - 2)(x - 3)$.

25:::

26:::

$ stemin check algebra

INFO algebra is a valid content repository

4Sharestemin.app

Add a course by its address

github.com/alice/algebra

Added. 12 decks, ready to study.

Your courses

stemin-app/stemin-foundationsMathematics and physics

alice/algebraAlgebra, by Alice

5And beyondstemin.app

Mathematics and physicsCourses that come with the app.

No accountYour progress stays on this device. An account keeps it on all of them.

OfflineA course on your device opens with no network.

stemin checkThe open-source checker finds mistakes before you publish.

A home for the things you study

Card by card

Write what you know

Pass it on

And beyond

Start studying