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IB Mathematics: Applications and Interpretation HL · AHL 9: Differential Equations · AHL 9.1

Setting up and integrating Problem set B Answers

Skills

    1. (a) \(\dfrac{dC}{dt}=kC\)
    2. (b) \(\dfrac{dA}{dt}=kA^{1/4}\)
    1. (a) \(\dfrac{dd}{dt}=\dfrac{k}{d}\)
    2. (b) \(\dfrac{dl}{dt}=\dfrac{k}{l^2}\)
    1. (a) \(\dfrac{dV}{dt}=-kV^{1/3}\)
    2. (b) \(\dfrac{dI}{dt}=-\dfrac{k}{I}\)
    1. (a) \(y=-20 \sqrt{x} + x^{4}+c\)
    2. (b) \(y=-18e^{-\frac{t}{3}}+c\)
    3. (c) \(y=-3t + 12 \ln|t|+c\)
    4. (d) \(s=-\frac{3 \cos(4t)}{4}+c\)

In context

  1. \(\dfrac{dJ}{dt}=kJ(800-J)\)

  2. \(\dfrac{dJ}{dt}=\dfrac{kJ(900-J)}{t}\)

    1. (a) \(h=-20e^{-\frac{t}{4}}+c\)
    2. (b) 17.3 m

Stretch

    1. (a) \(F=4m + \frac{3}{m}+c\)
    2. (b) \(G=2t + 2e^{-3t}+c\)

jmaths.xyz · AI HL · AHL 9.1 Setting up differential equations and integrating dy/dx = f(x)