C2.2 Evaluate algebraic expressions that involve whole numbers.
Skill: evaluate algebraic expressions involving natural numbers
To evaluate an algebraic expression, variables must be replaced by numerical values and calculations must be performed according to the priority of operations.
When students work with formulas, they are evaluating expressions.
Substituting variables with numerical values often requires the use of parentheses. For example, the expression 4c becomes 4(c) then 4 (5) when c = 5. The operation between 4 and 5 is understood to be a multiplication.
Source : Curriculum de l’Ontario. Programme-cadre de mathématiques de la 1re à la 8e année. 2020. Ministère de l’Éducation de l’Ontario.
Example 1
Evaluate the algebraic expression below, knowing that a = 25.
2a + 200
= 2 (25) + 200
= 50 + 200
= 250
Example 2
The base of a rectangle is 3 decimeters and its height is 4 decimeters. What is its area?
b × h
= 3 × 4
= 12
The area of the rectangle is 12dm2.