L16 · Functions that model linear relationships

1. 1.

   A function is f(x) = 5x + 5. Find f(8).

   Answer. 45

   f(8) = 5(8) + 5 = 45.

2. 2.

   A function is f(x) = 3x + 4. Find f(7).

   Answer. 25

   f(7) = 3(7) + 4 = 25.

3. 3.

   A function is f(x) = 5x + 10. Find f(9).

   Answer. 55

   f(9) = 5(9) + 10 = 55.

4. 4.

   A function is f(x) = 3x + 1. Find f(5).

   Answer. 16

   f(5) = 3(5) + 1 = 16.

5. 5.

   A function is f(x) = 3x + 8. Find f(6). Then Priya needs 5 of that amount. What is the total they need?

   Answer. 130

   f(6) = 3(6) + 8 = 26. Then multiply by 5: 130.

6. 6.

   A function is f(x) = 2x + 8. Find f(7). Then Luis needs 5 of that amount. What is the total they need?

   Answer. 110

   f(7) = 2(7) + 8 = 22. Then multiply by 5: 110.

7. 7.

   A function is f(x) = 4x + 7. Find f(5). Then Malik needs 2 of that amount. What is the total they need?

   Answer. 54

   f(5) = 4(5) + 7 = 27. Then multiply by 2: 54.

8. 8.

   A function is f(x) = 2x + 8. Find f(5). Then Ava needs 3 of that amount. What is the total they need?

   Answer. 54

   f(5) = 2(5) + 8 = 18. Then multiply by 3: 54.

9. 9.

   A function is f(x) = 4x + 3. Find f(3). Then Grace needs 3 of that amount. What is the total they need?

   Answer. 45

   f(3) = 4(3) + 3 = 15. Then multiply by 3: 45.

10. 10.

    A function is f(x) = 4x + 4. Find f(3). Then Priya needs 4 of that amount. What is the total they need?

    Answer. 64

    f(3) = 4(3) + 4 = 16. Then multiply by 4: 64.

11. 11.

    Think

    Ava tried this problem:
    A function is f(x) = 5x + 8. Find f(4).
    Ava wrote 29. That is not correct. What is the right answer?

    Answer. 28

    Ava’s answer 29 is off. f(4) = 5(4) + 8 = 28.

12. 12.

    Think

    Owen tried this problem:
    A function is f(x) = 6x + 5. Find f(5).
    Owen wrote 70. That is not correct. What is the right answer?

    Answer. 35

    Owen’s answer 70 is off. f(5) = 6(5) + 5 = 35.

Original extra practice. Keys are computed from the items, not guessed.