Applications of Integrals · Centroids & Averages

Net Change Theorem

abF(x)dx=F(b)F(a)\int_a^b F'(x)\, dx = F(b) - F(a)

The integral of a rate of change gives the net change. This is just FTC Part 2 interpreted in context.

  • 0 variables
  • 2 worked examples
  • 14 in Applications of Integrals

Worked examples

A population grows at rate P'(t) = 100e^(0.02t). Find the population increase from t = 0 to t = 10.
  1. ∫₀¹⁰ 100e^(0.02t) dt = 100[e^(0.02t)/0.02]₀¹⁰ = 5000(e^0.2 - 1)

Answer: 5000(e^0.2 - 1) ≈ 1107 individuals

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Water flows into a tank at r(t) = 6t litres per minute. How much water enters between t = 2 and t = 5 minutes?

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Practice

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