Differential Equations Answers

A cup of coffee (temperature = 190°F) is placed in a room whose temperature is 70°F. After five minutes, the temperature of the coffee has dropped to 160°F. How many more minutes must elapse before the temperature of the coffee is 130°F?

find the orthogonal trajectories of the family of hyperbolas xy=c (c not= 0 )

Solve Z^3=pqxy

Solve Z(p^2+q^2)+px+qy=0

A certain population is known to be growing at a rate given by the logistic equation dx/dt=x(b-ax),where a and b are positive constants .
Show that the maximum rate of growth will occur when the population is equal to half the equilibrium size, that is, when the population is (b/2a).

Find the complete integral of the equation
2u1xz+3u2z^2+u2^2u3=0
using Jacobi's method

Use the method of reduction of order to solve the following equation
(D^2+1)y=cosecx

Please solve the linear differential equations
1. dx/y+z = dy/-(x+z) = dz/x-y

2.(x^2D^2-3xD+5)y =x^2(logx)

q+xp=p^2

yz(y+z)dx+zx(z+x)dy+xy(x+y)dz=0