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Grade 9 · Math · Algebra 1

9th grade Complete the square, and solve by completing the square worksheet

6 printable versionsOn Level10 questions · answer keyFree · no account

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Complete the square, and solve by completing the square

Grade 9 Math Worksheet

NameDate

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

  1. Noah solves x² + 6x = 16 with algebra tiles and one missing corner. What is the smaller solution?

  2. Pia solves x² - 6x = 16 (the eraser is on standby). What is the larger solution?

  3. Tala solves x² + 8x - 9 = 0 by completing the square. What is the smaller solution?

  4. Zee plans a quilt pattern using x² - 10x - 24 = 0. What is the smaller solution?

  5. In math club, Ari solves x² + 10x - 24 = 0. What is the smaller solution?

  6. Bo's robot solves x² - 16x - 36 = 0 by completing the square. What is the larger solution?

  7. Esme rewrites x² + 10x + 18 as (x + 5)² + k. What is k?

  8. Jun rewrites x² - 6x + 4 as (x - 3)² + k to find the lowest row of its table. What is k?

  9. Luz uses tiles to rewrite x² + 8x + 21 as (x + 4)² + k. What is k?

  10. Milo's robot rewrites x² - 14x + 40 as (x - 7)² + k. What is k?

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9th grade Complete the square, and solve by completing the square worksheet – printable
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About this worksheet

Complete the square, and solve by completing the square. Every version has 10 questions, and the answer key prints on the second page.

What your child will learn

  • I can find the number that completes x² + 10x into a perfect square.
  • I can add it to both sides and solve with both roots.
  • I can rewrite x² + 10x + 18 as (x + 5)² - 7.

Standard: A-REI.B.4a, A-SSE.B.3b

Words to know

complete the square: Add the corner number so the expression is a bracket squared.

corner: The small square (half of the x number, squared) that fills the gap.

perfect square: A bracket times itself, like (x + 5)².

vertex form: a(x - h)² + k: the lowest (or highest) row of the table.

both sides: Whatever is added on the left is added on the right.

Common mistakes

Your child added half of the x number instead of half of it squared.

Your child squared the whole x number instead of half of it.

Your child put the whole x number in the bracket.

What to say

Ask: if each strip is 5 wide, how big is the corner square?

Ask: the 10x is split into two strips; how wide is each?

Ask: what is (x + 12)² multiplied out?

Questions parents ask

What is the most common mistake with complete the square, and solve by completing the square?

Your child added half of the x number instead of half of it squared.

How can I help my child with complete the square, and solve by completing the square?

Ask: if each strip is 5 wide, how big is the corner square?

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.

More algebra 1

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