Evaluating Expressions and Combining Like Terms
Evaluate algebraic expressions in Grade 10 by substituting values and simplify by combining like terms—terms with identical variables and exponents—to reduce expressions to simplest form.
Key Concepts
New Concept When you replace the variables in an expression with selected numbers and simplify using the order of operations, you have evaluated the expression.
Why it matters Algebra provides the language to describe complex systems, from physics to finance. Evaluating expressions is the critical skill that translates these abstract models into concrete, verifiable predictions.
What’s next Next, you'll practice substituting values for variables and combining like terms to simplify expressions.
Common Questions
How do you evaluate 3x²-2x+5 when x=-2?
Substitute x=-2: 3(-2)²-2(-2)+5 = 3(4)+4+5 = 12+4+5 = 21.
How do you combine like terms in 4x²-3x+7+2x²+5x-2?
Group like terms: (4x²+2x²)+(-3x+5x)+(7-2) = 6x²+2x+5.
Why must like terms have identical variable parts to be combined?
Like terms must have the same variable raised to the same power because they represent the same type of quantity. 3x² and 5x³ cannot be combined — squaring and cubing give different units.