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Grade 12 · Math · Calculus

12th grade Limit laws and direct substitution worksheet

6 printable versionsChallenge Me10 questions · answer keyFree · no account

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Limit laws and direct substitution

Grade 12 Math Worksheet - Challenge Me

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

  1. Ari substitutes first to find the limit of (x² − 4)/(x − 2) as x → 2. That gives a top of 0 and a bottom of 0. What should Ari conclude?

    • substitute: the limit is 0
    • k/0: no finite limit
    • 0/0: cancel (x − 2) first
  2. Bo substitutes first to find the limit of (x + 3)/(x − 1) as x → 1. That gives a top of 4 and a bottom of 0. What should Bo conclude?

    • 4/0: no finite limit
    • substitute: the limit is 0
    • 0/0: rewrite it first
  3. Esme substitutes first to find the limit of (x² − 9)/(x + 3) as x → -3. That gives a top of 0 and a bottom of 0. What should Esme conclude?

    • k/0: no finite limit
    • substitute: the limit is 0
    • 0/0: cancel (x + 3) first
  4. g(1) = 4; f(1) = 8; f(4) = 9. Luz wants the limit of f(g(x)) as x → 1, using the table shown. Both functions are smooth. What is the limit?

  5. g(-1) = 3; f(-1) = -4; f(3) = 2. Milo wants the limit of f(g(x)) as x → -1, using the table shown. Both functions are smooth. What is the limit?

  6. g(3) = -2; f(3) = 10; f(-2) = 5. Noah wants the limit of f(g(x)) as x → 3, using the table shown. Both functions are smooth. What is the limit?

  7. Pia is told that the limit of 3x² + kx as x → 2 is 20. What is k?

  8. Ren is told that the limit of 2x² + kx as x → 3 is 12. What is k?

  9. Tala is told that the limit of 5x² + kx as x → -1 is 9. What is k?

  10. Zee is told that the limit of 4x² + kx as x → 2 is 6. What is k?

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12th grade Limit laws and direct substitution worksheet – printable
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About this worksheet

Limit laws and direct substitution. Every version has 10 questions, and the answer key prints on the second page.

What your child will learn

  • I can combine given limits with the sum, multiple, power and root laws.
  • I can find a limit of a polynomial, rational function or model by substitution.
  • I can tell 0/0 from k/0 after substituting, and use a limit to find a constant.

Standard: none (beyond CCSS)

Words to know

limit laws: Rules that let a limit pass through +, −, ×, ÷, powers and roots.

direct substitution: Putting x = a in, which works when the function is smooth at a.

0/0: Top and bottom both 0: rewrite before deciding.

k/0: A nonzero top over 0: the values grow without bound.

Common mistakes

Combined the limits but dropped the numbers in front. The constant-multiple law keeps them: lim 3f = 3 lim f.

Subtracted a negative as if it were positive. Taking away −6 adds 6.

Squared a negative number and kept the minus. (−2)² = 4: a square is never negative.

Questions parents ask

What is the most common mistake with limit laws and direct substitution?

Combined the limits but dropped the numbers in front. The constant-multiple law keeps them: lim 3f = 3 lim f.

Are these 12th 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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