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← 📐 Mathematics · usually met in Std 6-12

Algebra

Arithmetic with letters standing in for numbers — which lets you state a rule once instead of solving the same problem endlessly.

A variable is a placeholder for a number you do not yet know, or for any number at all. An equation says two expressions are equal, and solving it means finding which values make that true. The one rule underneath all the technique is that whatever you do to one side you must do to the other, because that is what keeps the statement true.

The power of it is generality. The area of any rectangle is length times breadth, written once, for every rectangle there will ever be. The word comes from al-jabr in the title of a ninth-century work by al-Khwarizmi, whose own name gave us algorithm; Indian mathematicians including Brahmagupta and Bhaskara had been solving such equations earlier still.

Worth knowing

  • A quadratic equation can have two solutions, one, or none among the real numbers.
  • Bhaskara II in the twelfth century worked on equations and on ideas that anticipate calculus.
  • Most mistakes in school algebra are sign errors, not conceptual ones — which is why writing each step out pays.

Want to see it moving? Search YouTube for “Algebra” ↗ — we send you to the search rather than to one video, because a link to one video eventually rots.

See also

📐 Number systems📐 Geometry📐 Statistics and probability

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Last gone through: 1 October 2026 · How these entries are written

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