Year 8: Numeric substitution in algebraic expressions

What is Numeric Substitution?

In algebra, we use letters (variables) to represent numbers. Numeric substitution means replacing these letters with actual numerical values to evaluate an algebraic expression. It's like plugging numbers into a formula.

Example:

Let's say we have the expression: 2x + 3

If we know that x = 4, we substitute 4 for every ‘x’ in the expression.

So, 2(4) + 3

Which simplifies to 8 + 3 = 11

Steps for Numeric Substitution:

1. Identify the Variable: Find the letter(s) in the expression that represents a number.
2. Replace the Variable: Substitute the given numerical value into the expression, replacing every instance of the variable with that number.
3. Simplify: Perform the arithmetic operations to simplify the expression and get the final numerical answer.

Important Notes:

• Make sure you understand the order of operations (BODMAS/PEMDAS) when simplifying.
• Pay close attention to signs (positive and negative) when substituting numbers.
• Carefully follow the substitution rules to avoid errors.