Algebra Basics
Introduction to algebra, including variables, expressions, and simple equations.
Introduction to Algebra
Algebra uses letters to represent unknown numbers. It's like solving puzzles!
What is a Variable?
A variable is a letter that stands for a number we don't know yet. Common letters: x, y, n, a, b.
Algebraic Expressions
An expression is a combination of numbers and variables.
- x + 5 means x plus 5
- 3y means 3 times y (we don't write the x sign)
- 2a + 7 means 2 times a, plus 7
Substituting Values
If x = 4: x + 7 = 11, 3x = 12, x2 = 16
Simplifying Expressions
Collect like terms (same variable):
- 3x + 5x = 8x
- 7y - 2y = 5y
- 4a + 3 + 2a + 6 = 6a + 9
Solving Simple Equations
An equation has an = sign. Find the value of the variable.
Example: x + 7 = 12. Subtract 7 from both sides. x = 5. Example: 3x = 18. Divide both sides by 3. x = 6. Example: 2x + 5 = 13. Subtract 5: 2x = 8. Divide by 2: x = 4.
Check Your Answer
Always substitute back: 2(4) + 5 = 8 + 5 = 13. Correct!
Practice Problems
- If y = 3, evaluate: 2y + 4 = ?
- Simplify: 5a + 3a - 2a = ?
- Solve: x + 9 = 15
- Solve: 4n = 24
- Solve: 3x - 4 = 11
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