What Is Algebra?
Algebra is a branch of mathematics where we use letters (called variables) to represent unknown numbers.
Key Terms
- Variable: a letter like x, y, or n representing an unknown
- Constant: a fixed number like 5, 12, or 100
- Expression: a combination of variables and constants, e.g. 3x + 5
- Equation: an expression set equal to a value, e.g. 3x + 5 = 14
- Coefficient: the number multiplying a variable (in 3x, the coefficient is 3)
Simplifying Expressions
Collect like terms (terms with the same variable):
4x + 3y + 2x − y = 6x + 2y
Solving Simple Equations
Find x: 2x + 7 = 15
Step 1: 2x = 15 − 7 = 8
Step 2: x = 8 ÷ 2 = 4
Check: 2(4) + 7 = 8 + 7 = 15 ✓
💡 Whatever you do to one side of an equation, do the same to the other side.