algebra

Everyday

1. Algebra is the part of maths that uses letters and symbols, such as x or n, to stand for numbers that are unknown or that can change. tree →
2. Algebra is also the rules for working with these letters in expressions, equations and formulas. tree →

In the lessons

In school maths algebra starts with missing number problems (□ + 3 = 7) and grows into equations (x + 3 = 7, so x = 4), formulas (area = length × width) and sequences (the nth term is 2n + 1). The word comes from Arabic «al-jabr», from a book by the Persian scholar al-Khwarizmi. Phrases: do algebra, algebra lesson, solve with algebra.

Examples

• In algebra, we can use n to stand for any number. tree →
• Algebra helps us solve problems like «I think of a number, add 5 and get 12». tree →
• If 2x = 10, algebra tells us x = 5. tree →
• Our algebra homework was about simplifying expressions. tree →
• The formula for the perimeter of a square is P = 4s; that's algebra. tree →
• The word algebra comes from Arabic. tree →
• My big sister says algebra is like a puzzle with letters. tree →
• Then he tried to do the sum by algebra, by simple and by quadratic equations, by trigonometry, by logarithms, and by conic sections. tree →

Note

Uncountable: «some algebra», not «an algebra» (except in university maths). In algebra 3n means 3 × n, and n² means n × n. A letter in one problem keeps the same value throughout that problem. Adjective: algebraic.