Evaluating Algebraic Expressions
This Grade 6 math skill from Pengi Math (Grade 6) teaches students to evaluate algebraic expressions by substituting given values for variables and simplifying using the order of operations. Students practice replacing letters with numbers and computing the resulting numerical expression step by step.
Key Concepts
Property When we evaluate an algebraic expression, we follow the order of operations. Order of Operations: 1. Perform any operations inside parentheses, or above or below a fraction bar. 2. Perform all multiplications and divisions from left to right. 3. Perform additions and subtractions from left to right.
Examples Evaluate $30 4x$ for $x=2$. Substitute: $30 4(2)$. Multiply: $30 8$. Finally, subtract: $22$. Evaluate $2(a + 1)$ for $a=5$. Substitute: $2(5+1)$. Add: $2(6)$. Finally, multiply: $12$. Evaluate $7(b + 3) + 5$ for $b=2$. Substitute: $7(2 + 3) + 5$. Add: $7(5) + 5$. Then, multiply: $35+5$. Finally, add: $40$.
Explanation Evaluating an expression means finding its final numerical value. The Order of Operations is the universal rulebook that ensures everyone gets the same answer from the same calculation. Always follow the steps precisely.
Common Questions
How do you evaluate an algebraic expression?
Replace each variable with the given numerical value, then simplify the resulting expression using the order of operations (PEMDAS).
What is the order of operations?
The order of operations is Parentheses, Exponents, Multiplication and Division (left to right), and Addition and Subtraction (left to right), remembered as PEMDAS.
What does it mean to substitute a value into an expression?
Substitution means replacing a variable with a specific number. For example, evaluating 3x + 2 when x = 4 gives 3(4) + 2 = 14.
Can an algebraic expression have more than one variable?
Yes. To evaluate an expression with multiple variables, substitute a specific value for each variable, then simplify.
Where is evaluating algebraic expressions taught in Grade 6?
This skill is part of the Grade 6 Pengi Math textbook, covering foundational algebra concepts.