Monotone Convergence, Fatou and Dominated Convergence · seed 1 · A4, ink-friendly. The answer key prints on its own page for grown-ups.

When limits may pass inside the integral

Mathematics · Calculus & Analysis · ages 22-24
Name ______________________   Date ____________
  1. Constant 0.5 on the interval from 0 to 0.5. Integral is product. What is it?

    Answer: ______________

  2. Which hypothesis lets the limit pass inside the integral for an increasing nonnegative sequence?

    • Decreasing to negative infinity
    • Monotone increasing to the limit
    • No hypotheses
    • Sequence is constant zero
  3. Non-negative functions climb steadily up to f. What does monotone convergence conclude?

    • The integrals climb to the integral of the limit
    • The limit function must be continuous
    • Every function in the climb is bounded
  4. Dominated convergence needs one integrable function sitting above the whole sequence.

    Circle one:   True   False

  5. Which function dominates the sliding bumps?

    • The constant function 1
    • The limit function 0
    • None with a finite integral exists
  6. If no integrable dominating function exists, dominated convergence does not apply and limit and integral may differ. Is this correct?

    Circle one:   True   False

  7. Which sequence gives strict Fatou inequality?

    • Constants 1, 1, dots
    • Zeros 0, 0, dots
    • Increasing to the limit
    • Bumps escaping to infinity, indicator of [n, n plus 1]
  8. In a monotone convergence argument, where is monotonicity actually used?

    • To prove each function is continuous
    • To order the functions alphabetically by name
    • To guarantee the integrals climb along with the functions
  9. Integrals stay at 1 but the limit integrates to 0. Which hypothesis failed?

    • No climbing and no integrable ceiling, so neither theorem applies
    • The bump functions are not measurable
    • The limit was taken pointwise instead of uniformly
  10. Function raises its input to the fourth power on [0, 1]. What is its integral as a decimal?

    Answer: ______________

LightMySky · lightmysky.comW1-mt_7n6ZDkHeBe-s1

Answer key

For grown-ups. Fold this page away before handing over the rest.

When limits may pass inside the integral W1-mt_7n6ZDkHeBe-s1

  1. 0.25 · 0.5 times 0.5 equals 0.25.
  2. Monotone increasing to the limit · Monotone increasing to the limit triggers monotone convergence, while the other options lack the needed structure.
  3. The integrals climb to the integral of the limit · Increasing functions let the limit pass inside the integral.
  4. True · That ceiling is what keeps mass from escaping.
  5. None with a finite integral exists · Any ceiling must sit above 1 on every bump, covering the whole half line.
  6. True · Domination is essential for the theorem.
  7. Bumps escaping to infinity, indicator of [n, n plus 1] · Bumps escaping to infinity, indicator of [n, n plus 1] keeps integral 1 with zero limit, while constants, zeros, and increasing cases give equality.
  8. To guarantee the integrals climb along with the functions · Climbing functions give climbing integrals, and that order carries the proof.
  9. No climbing and no integrable ceiling, so neither theorem applies · The bumps neither climb nor sit under one integrable ceiling.
  10. 0.2 · Antiderivative is x to the fifth divided by 5, evaluating to 0.2.
Worksheet · LightMySky