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Algebra foundations
The art of working with the unknown.
Algebra is arithmetic with a placeholder: a letter standing for a number you don't know yet. That one move — naming the unknown — turns puzzles you'd solve by guessing into puzzles you solve by steps.
Your progress
4 lessons
The big ideas
The unknown has a name
Calling a mystery number x doesn't solve anything by itself — but it lets you write down what you do know, and push on it.
Balance is the rule
An equation is a scale. Whatever you do to one side, do to the other, and the truth of it never breaks. Solving is just rebalancing until x stands alone.
Patterns become formulas
When the same calculation works for every number, algebra writes it once: area = l × w. A formula is a story about all numbers at the same time.
The course — start at lesson one
Out in the world
Budgeting & pricing
“How many months until I can afford it?” is a one-variable equation you already solve informally.
Spreadsheets
Every spreadsheet formula is algebra: cells are variables, formulas are expressions over them.
Code
Variables, expressions, and solving for conditions — programming is algebra that executes.
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