2.3 Quiz

What is the order of the following equations

1. {{∂}^{3}u\over ∂{x}^{3}} + {{∂}^{2}u\over ∂{y}^{2}} = 0

   (2.7)

2. {{∂}^{2}u\over ∂{x}^{2}} − 2 {{∂}^{4}u\over ∂{x}^{3}u} + {{∂}^{2}u\over ∂{y}^{2}} = 0

   (2.8)

Classify the following differential equations (as elliptic, etc.)

1. {{∂}^{2}u\over ∂{x}^{2}} − 2 {{∂}^{2}u\over ∂x∂y} + {{∂}^{2}u\over ∂{y}^{2}} = 0

2. {{∂}^{2}u\over ∂{x}^{2}} + {{∂}^{2}u\over ∂{y}^{2}} + {∂u\over ∂x} = 0

3. {{∂}^{2}u\over ∂{x}^{2}} −{{∂}^{2}u\over ∂{y}^{2}} + 2{∂u\over ∂x} = 0

4. {{∂}^{2}u\over ∂{x}^{2}} + {∂u\over ∂x} + 2{∂u\over ∂y} = 0

5. y{{∂}^{2}u\over ∂{x}^{2}} + x{{∂}^{2}u\over ∂{y}^{2}} = 0