Year 9: Symbolic substitution in algebraic expressions

What is Symbolic Substitution?

Symbolic substitution is a technique used in algebra where you replace a variable in an expression with a specific value. It's like plugging in a number for the variable to see what the whole expression equals.

How to do it:

1. Identify the Variable: Find the variable in the expression (e.g., x, y, a).
2. Replace with a Value: Replace the variable with the given value.
3. Simplify: Simplify the resulting expression.

Example:

Given the expression: 3xx + 2

If x = 4, what is the value of the expression? 3(4) + 2 = 12 + 2 = 14

Another Example:

Given the expression: 2y² - 5y + 1

If y = -2, then substitute: 2(-2)² - 5(-2) + 1 = 2(4) + 10 + 1 = 8 + 10 + 1 = 19

Important Note: Make sure you perform the operations in the correct order (PEMDAS/BODMAS) after substituting the value.