Evaluate 5x + 2 for x = 5.
27
Substitute first: 5 × 5 + 2 = 27.
Day 084Substitution and Evaluation
Standards 6.EE.A.2c
LEARNING TARGET
I can substitute values and evaluate expressions or formulas.
01 · LEARN
Build the idea
Replace every variable with its assigned value, using parentheses. Apply the order of operations. In formulas, label the answer with the appropriate measurement units.
A rectangle has length x + 2 and width 6. Use A = lw to write its area expression and find A when x = 2.
A = 6(x + 2); 24 square units
Substitute x = 2: 6(2 + 2) = 24.
02 · PRACTICE
Your turn
Work in order. Start with the foundations, then build toward explanation and application.
Evaluate 7x + 6 for x = 2.
Evaluate 8x + 6 for x = 5.
Evaluate 2x + 6 for x = 4.
Evaluate x^2 + 2y for x = 4 and y = 4.
Evaluate x^2 + 8y for x = 5 and y = 4.
Evaluate x^2 + 7y for x = 5 and y = 3.
A rectangle has length x + 5 and width 6. Use A = lw to write its area expression and find A when x = 4.
A rectangle has length x + 6 and width 6. Use A = lw to write its area expression and find A when x = 3.
A rectangle has length x + 2 and width 3. Use A = lw to write its area expression and find A when x = 6.
A rectangle has length x + 4 and width 4. Use A = lw to write its area expression and find A when x = 3.
03 · CHECK
Answers and reasoning
Reveal the teacher answer key
- 20
Substitute first: 7 × 2 + 6 = 20.
- 46
Substitute first: 8 × 5 + 6 = 46.
- 14
Substitute first: 2 × 4 + 6 = 14.
- 24
Substitute first: 4^2 + 2 × 4 = 24.
- 57
Substitute first: 5^2 + 8 × 4 = 57.
- 46
Substitute first: 5^2 + 7 × 3 = 46.
- A = 6(x + 5); 54 square units
Substitute x = 4: 6(4 + 5) = 54.
- A = 6(x + 6); 54 square units
Substitute x = 3: 6(3 + 6) = 54.
- A = 3(x + 2); 24 square units
Substitute x = 6: 3(6 + 2) = 24.
- A = 4(x + 4); 28 square units
Substitute x = 3: 4(3 + 4) = 28.