What is the order and type of the ff PDE's.
1.
(1+X^2)Uxxyy-2xy^3Uxyyy+(1+u^2)UYY=0
2.(1+U^2)Uxx-2U^2Uxy+(1+u^2)UYY=0
3.(1+X^2Y)Uxx-2UXUyUxy+(1+u^2X)UYY=0
3. Solve the following differential equation
x^2y’’ − 2xy’ + 5y = 0.
A coil spring is suspended from the ceiling, a 16-lb weight is
attached to the end of it, and the weight then comes to rest in its
equilibrium position. The mass is in a medium that exerts a viscous
resistance of 8 lb when the mass has a velocity of 1 ft/s. It is
then pulled down 12 in. below its equilibrium position and released
with an...