Introduction to Algebra
Variables, expressions and simple equations
Learn to use letters to represent unknown numbers and solve basic equations.
📖 Understanding Introduction to Algebra
Algebra uses letters (variables) to represent unknown or changing numbers. For example, if x is a number and we know x + 5 = 12, we can find that x = 7.
An expression is a mathematical phrase with numbers, variables and operations. Examples: 3x + 2, 5a − b, 2(x + 3). An expression does not have an equals sign.
An equation has an equals sign and states that two expressions are equal. Solving an equation means finding the value of the variable that makes the equation true.
Golden rule of algebra: whatever you do to one side of the equation, you must do to the other side. This keeps the equation balanced.
🔑 Key Points to Remember
- ✓Variable: a letter representing an unknown number
- ✓Expression: has no = sign (e.g. 3x + 2)
- ✓Equation: has = sign (e.g. 3x + 2 = 14)
- ✓Solve by doing inverse operations
- ✓Like terms: same variable, same power (3x and 5x are like terms)
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