Example 7 For each of the differential equations indicate whether it is linear or nonlinear. 1. ln(x)*(d^(2)y/dx^2) 3e^(x)*(dy/dx) y sin(x)=0 Answer: ? 2. 2y 3y^2 =ex Answer: ? 3. d^(3)y/dx^(3) (x^2 1)y cos(x)=0 4. y sin(x y)y (x^2 1)y = 0 5. y e^(xy) = cos(2x y)