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Evaluating Functions: Classroom Packet

Grade 8 Algebra: Evaluating Functions

Name: ______________________Date: ____________Score: ____ / 8

Level 1

Whole-number inputs

1. Evaluate:
$f(x) = x + 5;\ f(3)$
2. Evaluate:
$f(x) = 2x;\ f(6)$
3. Evaluate:
$f(x) = x - 4;\ f(10)$
4. Evaluate:
$f(x) = 3x + 1;\ f(2)$
5. Evaluate:
$f(x) = 5x - 3;\ f(4)$
6. Evaluate:
$f(x) = 10 - x;\ f(7)$
7. Evaluate:
$f(x) = 4x + 2;\ f(0)$
8. Evaluate:
$f(x) = \tfrac{x}{2} + 1;\ f(8)$

Answer Key

Level 1

1. $8$
2. $12$
3. $6$
4. $7$
5. $17$
6. $3$
7. $2$
8. $5$

Grade 8 Algebra: Evaluating Functions

Name: ______________________Date: ____________Score: ____ / 8

Level 2

Negatives, fractions and squares

1. Evaluate:
$f(x) = 2x + 3;\ f(-4)$
2. Evaluate:
$g(x) = -3x + 1;\ g(2)$
3. Evaluate:
$h(x) = x^2 + 1;\ h(-3)$
4. Evaluate:
$f(x) = \tfrac{1}{2}x - 2;\ f(-6)$
5. Evaluate:
$g(x) = x^2 - 2x;\ g(4)$
6. Evaluate:
$f(x) = -x + 8;\ f(-2)$
7. Evaluate:
$h(x) = \tfrac{3}{4}x;\ h(12)$
8. Evaluate:
$f(x) = 2x^2 - 5;\ f(3)$

Answer Key

Level 2

1. $-5$
2. $-5$
3. $10$
4. $-5$
5. $8$
6. $10$
7. $9$
8. $13$

Grade 8 Algebra: Evaluating Functions

Name: ______________________Date: ____________Score: ____ / 8

Level 3

Solving and combining

1. Find ${x}$ :
$f(x) = 2x + 3;\ f(x) = 11$
2. Find ${x}$ :
$f(x) = 5x - 7;\ f(x) = -2$
3. Find ${x}$ :
$g(x) = -4x + 6;\ g(x) = 18$
4. Evaluate:
$f(x) = 3x - 1;\ f(2) + f(-1)$
5. Evaluate:
$f(x) = x^2,\ g(x) = 2x + 1;\ f(3) - g(3)$
6. Find ${x}$ :
$f(x) = \tfrac{x}{3} + 4;\ f(x) = 6$
7. Evaluate:
$f(x) = 2x - 1;\ f(f(2))$
8. Find ${x}$ :
$f(x) = -2x + 9;\ f(x) = x$

Answer Key

Level 3

1. $x = 4$
2. $x = 1$
3. $x = -3$
4. $1$
5. $2$
6. $x = 6$
7. $5$
8. $x = 3$