Evaluate 2x + 6 for x = 6.
18
Substitute first: 2 × 6 + 6 = 18.
Day 086Evaluating Formulas
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 2. Use A = lw to write its area expression and find A when x = 3.
A = 2(x + 2); 10 square units
Substitute x = 3: 2(3 + 2) = 10.
02 · PRACTICE
Your turn
Work in order. Start with the foundations, then build toward explanation and application.
Evaluate 2x + 2 for x = 6.
Evaluate 8x + 4 for x = 6.
Evaluate 4x + 6 for x = 2.
Evaluate x^2 + 8y for x = 5 and y = 5.
Evaluate x^2 + 5y for x = 5 and y = 6.
Evaluate x^2 + 8y for x = 3 and y = 3.
A rectangle has length x + 7 and width 6. Use A = lw to write its area expression and find A when x = 6.
A rectangle has length x + 5 and width 4. Use A = lw to write its area expression and find A when x = 4.
A rectangle has length x + 5 and width 5. Use A = lw to write its area expression and find A when x = 5.
A rectangle has length x + 4 and width 6. Use A = lw to write its area expression and find A when x = 6.
03 · CHECK
Answers and reasoning
Reveal the teacher answer key
- 14
Substitute first: 2 × 6 + 2 = 14.
- 52
Substitute first: 8 × 6 + 4 = 52.
- 14
Substitute first: 4 × 2 + 6 = 14.
- 65
Substitute first: 5^2 + 8 × 5 = 65.
- 55
Substitute first: 5^2 + 5 × 6 = 55.
- 33
Substitute first: 3^2 + 8 × 3 = 33.
- A = 6(x + 7); 78 square units
Substitute x = 6: 6(6 + 7) = 78.
- A = 4(x + 5); 36 square units
Substitute x = 4: 4(4 + 5) = 36.
- A = 5(x + 5); 50 square units
Substitute x = 5: 5(5 + 5) = 50.
- A = 6(x + 4); 60 square units
Substitute x = 6: 6(6 + 4) = 60.