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Grade 9 · Math

Read a quadratic’s vertex form

Find the vertex’s x-coordinate from a completed-square expression.

8 authored questions + worked example

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Worked example

For y = (x + 4)2 + 3, what is the x-coordinate of the vertex?

Answer & why

Answer: -4

The squared term is zero when x = -4. The vertex is (-4, 3), so its x-coordinate is -4.

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All questions

All 8 authored questions for this skill.

Question 1

For y = (x − 2)2 − 6, what is the x-coordinate of the vertex?

  1. 2
  2. 4
  3. 3
  4. 1
A hint

In y=(x−h)2+k, the vertex is (h,k).

Answer & why

Answer: 2

The squared term is zero when x = 2. The vertex is (2, -6), so its x-coordinate is 2.

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Question 2

For y = (x − 4)2 + 1, what is the x-coordinate of the vertex?

  1. 5
  2. 4
  3. 6
  4. 3
A hint

In y=(x−h)2+k, the vertex is (h,k).

Answer & why

Answer: 4

The squared term is zero when x = 4. The vertex is (4, 1), so its x-coordinate is 4.

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Question 3

For y = (x + 4)2 + 3, what is the x-coordinate of the vertex?

  1. -2
  2. -3
  3. -4
  4. -5
A hint

In y=(x−h)2+k, the vertex is (h,k).

Answer & why

Answer: -4

The squared term is zero when x = -4. The vertex is (-4, 3), so its x-coordinate is -4.

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Question 4

For y = (x + 2)2 − 1, what is the x-coordinate of the vertex?

  1. -2
  2. -1
  3. -3
  4. 0
A hint

In y=(x−h)2+k, the vertex is (h,k).

Answer & why

Answer: -2

The squared term is zero when x = -2. The vertex is (-2, -1), so its x-coordinate is -2.

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Question 5

For y = (x − 1)2 + 5, what is the x-coordinate of the vertex?

  1. 2
  2. 1
  3. 0
  4. 3
A hint

In y=(x−h)2+k, the vertex is (h,k).

Answer & why

Answer: 1

The squared term is zero when x = 1. The vertex is (1, 5), so its x-coordinate is 1.

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Question 6

For y = (x − 3)2 − 2, what is the x-coordinate of the vertex?

  1. 3
  2. 4
  3. 5
  4. 2
A hint

In y=(x−h)2+k, the vertex is (h,k).

Answer & why

Answer: 3

The squared term is zero when x = 3. The vertex is (3, -2), so its x-coordinate is 3.

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Question 7

For y = (x − 5)2 + 4, what is the x-coordinate of the vertex?

  1. 6
  2. 4
  3. 7
  4. 5
A hint

In y=(x−h)2+k, the vertex is (h,k).

Answer & why

Answer: 5

The squared term is zero when x = 5. The vertex is (5, 4), so its x-coordinate is 5.

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Question 8

For y = (x + 3)2 + 7, what is the x-coordinate of the vertex?

  1. -3
  2. -1
  3. -2
  4. -4
A hint

In y=(x−h)2+k, the vertex is (h,k).

Answer & why

Answer: -3

The squared term is zero when x = -3. The vertex is (-3, 7), so its x-coordinate is -3.

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