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Grade 9 · Math · Algebra 1

9th grade Direct variation y = kx and inverse variation xy = k worksheet

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Direct variation y = kx and inverse variation xy = k

Grade 9 Math Worksheet - Building Confidence

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

  1. Read this first

    Input–output table

    xy
    26

    Output ÷ input = k.

  2. 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. 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?

  4. 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?

  5. Input–output table

    xy
    46

    Input × output = k.

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

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

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

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

  10. 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?

  11. 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?

  12. 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?

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9th grade Direct variation y = kx and inverse variation xy = k worksheet – printable
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About this worksheet

Direct and inverse variation. Every version has 10 questions, and the answer key prints on the second page.

What your child will learn

  • I can find k from one pair for direct variation (y = kx) and for inverse variation (xy = k).
  • I can find a new value from one pair.
  • I can tell direct from inverse variation in a table or a rule.

Standard: state-only (A-CED.A.2 and F-LE.A.1b support)

Words to know

direct variation: y = kx. y ÷ x is the same in every row.

inverse variation: y = k ÷ x, so xy = k. x × y is the same in every row.

constant k: The number that stays the same: y ÷ x for direct, x × y for inverse.

Common mistakes

Your child multiplied the two numbers where k is output divided by input.

Your child divided the input by the output, which turns k upside down.

Your child divided where inverse variation multiplies.

What to say

Ask: for y = kx, what do you do to y to get k?

Ask: which number goes on top, the output or the input?

Ask: for xy = k, what do you do to x and y to get k?

Questions parents ask

What is the most common mistake with direct variation y = kx and inverse variation xy = k?

Your child multiplied the two numbers where k is output divided by input.

How can I help my child with direct variation y = kx and inverse variation xy = k?

Ask: for y = kx, what do you do to y to get k?

Are these 9th grade math worksheets free to print?

Yes. All 6 printable versions at each level are free to print, with the answer key, and no account is needed.

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