Evaluating an expression by substitution means replacing each variable with its given numerical value while preserving the expression’s structure, then calculating with parentheses, exponents, and the agreed order of operations. The understanding applies to expressions involving whole numbers, integers, fractions, and decimals, and distinguishes finding an expression’s value from solving an equation; it does not include symbolic simplification, advanced exponent rules, or complex rational expressions.
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Detailed Explanation: Evaluate expressions by substitution
To evaluate an expression by substitution:
- Replace each variable with its given value.
- Put negative numbers in parentheses.
- Calculate using the order of operations: parentheses, exponents, multiplication or division, then addition or subtraction.
Example: Evaluate when and .
Substitute the given values for the variables:
Now evaluate the exponent:
Multiply:
Subtract:
So, the value of is . Evaluating finds the value of an expression; it does not mean solving an equation.
Learn by doing: Evaluate expressions by substitution
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Practice:
Algebraic Function Variable Substitution - Simple Terms
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Download/Modify Free Grade 6 'Evaluate expressions by substitution' Worksheet
Print this free 'Evaluate expressions by substitution' worksheet to practice this skill away from the computer. Click 'Modify' to easily customize this worksheet to your exact needs.
This Worksheet Includes:
- Algebraic Function Variable Substitution - Simple Terms
- Algebraic Function Variable Substitution - Simple Terms (Negatives)
- Algebraic Function Variable Substitution - Bracketed Terms
- Algebraic Function Variable Substitution - Bracketed Terms (Negatives)
- Algebraic Function Variable Substitution - Simple Squared Terms
- Algebraic Function Variable Substitution - Fractional Terms
- Algebraic Functions - Variable Substitution to Equation - Simple Terms (Negatives)
- Algebraic Functions - Variable Substitution to Equation - Bracketed Terms
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