For the equation y″ + 8y′ + 12y = 0, find the root r of the characteristic equation that is closest to zero. It sets how slowly the solution dies out.
Differential equations worksheet with answers
1.Easy
y″ + 8y′ + 12y = 0
r =
2.Easy
For the equation y″ + 7y′ + 6y = 0, find the root r of the characteristic equation that is closest to zero. It sets how slowly the solution dies out.
y″ + 7y′ + 6y = 0
r =
3.Medium
A can of soda at 4 °C is taken out of the fridge into a room at 25 °C. After 6 min its temperature is 13 °C. It follows Newton's law of cooling, dT/dt = −k·(T − Tₐ). Find the constant k in min⁻¹.
T0 = 4 °CTa = 25 °CT(6) = 13 °C
k = min⁻¹
4.Medium
Solve y″ + 8y′ + 16y = 0 with y(0) = 2 and y′(0) = 1. Find y(2).
y″ + 8y′ + 16y = 0y(0) = 2y′(0) = 1
y(2) =
5.Hard
A system obeys y″ + 4y′ + 29y = 145 for t ≥ 0, starting from rest: y(0) = 0, y′(0) = 0. Find y(0.75); angles in radians.
y″ + 4y′ + 29y = 145y(0) = 0y′(0) = 0
y(0.75) =
6.Hard
Solve y′ + 2y = 4e−3t with y(0) = 3. Find y(1).
y′ + 2y = 4e−3ty(0) = 3
y(1) =
Answer key
- 1. r = −2
- 2. r = −1
- 3. k = 0.09327 min⁻¹
- 4. y(2) = 0.006709
- 5. y(0.75) = 6.171
- 6. y(1) = 0.7482
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