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Algebra Variables

Grades 6-9 · Concept Explainer

Key Points

  • ✓A variable is a symbol (usually a letter) representing an unknown number.
  • ✓Variables are used in equations to represent values we need to find.
  • ✓We can solve for variables by using algebraic operations to isolate them.
  • ✓Variables allow us to express relationships between numbers in a general way.
  • ✓Understanding variables is crucial for solving algebraic problems.

In algebra, a variable is a symbol, usually a letter, that represents an unknown number. Think of it as a placeholder for a value we haven't figured out yet. We use variables to write equations and solve problems where we need to find that missing number. For example, in the equation 'x + 3 = 7', 'x' is the variable. Our goal is to find the value of 'x' that makes the equation true. By using algebraic operations, we can isolate the variable and discover its value.

Worked Example

Solve for 'y' in the equation: 2y + 5 = 11

  1. Step 1: Subtract 5 from both sides of the equation: 2y + 5 - 5 = 11 - 5
  2. Step 2: Simplify: 2y = 6
  3. Step 3: Divide both sides by 2: 2y / 2 = 6 / 2
  4. Step 4: Simplify: y = 3

Answer: y = 3

Try It Yourself

1. Solve for 'a': a + 4 = 9

2. Solve for 'b': 3b - 2 = 10

3. Solve for 'c': 5c + 7 = 2c + 19

Watch Out For These Mistakes

  • Forgetting to perform the same operation on both sides of the equation.
  • Incorrectly combining like terms.
  • Not isolating the variable completely.