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: 3x$x+2$

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

Another example:

Given the expression: 2y² - 5y + 1

If y = -2, then substitute: $2{(-2)}^2-5(-2)+1=2\left(4\right)+10+1=8+10+1=19$

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