EDEXCEL GCSE FOUNDATION MATHS - What is Substitution

Edexcel GCSE Foundation Maths: What is Substitution?

Substitution is a fundamental concept in mathematics. It's a process where we replace a variable (a letter that represents a value) with a specific number or expression. This is often done in algebraic equations and formulas.

Example:

Let's say we have the formula for the area of a rectangle:

Area = length × width

And we know the length is 5 cm and the width is 3 cm.

To find the area, we substitute the values into the formula:

Area = 5 cm × 3 cm
Area = 15 cm²

Steps for Substitution:

1. Identify the variable you need to substitute. Look for the letter in the formula or equation.
2. Find the value of the variable. This might be given in the problem, or you may need to calculate it.
3. Replace the variable with its value. Make sure you use parentheses if necessary, especially when working with more complex expressions.
4. Simplify the expression. Perform the operations (addition, subtraction, multiplication, division) to get the final answer.

Important Note: When substituting values into formulas, ensure you use the correct units. In the example above, the area is measured in square centimeters (cm²).

Practice Problems:

1. Substitute the values into the formula for the perimeter of a square: Perimeter = 4 × side Given that the side length is 7 cm.

2. Substitute the values into the formula for the volume of a cube: Volume = side³ Given that the side length is 4 cm.

Understanding Substitution:

Substitution is a powerful tool in mathematics. It allows us to solve problems, analyze relationships, and apply formulas effectively. With practice, you'll become comfortable with this process and use it with ease.