Direct variation y = kx and inverse variation xy = k

Answer Key - Grade 9 Math Worksheet - Building Confidence

Circle the best answer, or write your answer on the line.

1. Read this first

   Input–output table

   x	y
   2	6

   Output ÷ input = k.

2. 1.

   On a worksheet, Milo learns that y varies directly with x, and y = 6 when x = 2. The constant k is y ÷ x. What is k?

   3
3. 2.

   In a puzzle book, Milo learns that y varies directly with x, and y = 10 when x = 4. The constant k is y ÷ x. What is k?

   5/2
4. 3.

   In the warm-up, Ren learns that y varies directly with x, and y = 9 when x = 6. The constant k is y ÷ x. What is k?

   3/2

5. Input–output table

   x	y
   4	6

   Input × output = k.

6. 4.

   Esme learns that y varies inversely with x, and y = 6 when x = 4. The constant k is x × y. What is k?

   24
7. 5.

   Noah learns that y varies inversely with x, and y = 10 when x = 3. The constant k is x × y. What is k?

   30
8. 6.

   Ari learns that y varies inversely with x, and y = 8 when x = 5. The constant k is x × y. What is k?

   40
9. 7.

   Luz learns that y varies inversely with x, and y = 9 when x = 2. The constant k is x × y. What is k?

   18
10. 8.

    The rule is y = 4x. Tala knows y varies directly with x, with k = 4. The rule is y = kx. What is y when x = 6?

    24
11. 9.

    The rule is xy = 30. Jun knows y varies inversely with x, with k = 30. The rule is xy = k. What is y when x = 5?

    6
12. 10.

    The rule is y = 5x. Pia knows y varies directly with x, with k = 5. The rule is y = kx. What is y when x = 7?

    35