Randolph College
Department of Mathematics and Computer Science

 

Homework # 5 - Math 328


The problems on this homework must be done alone.  The honor code is in effect.

 First name:   Last name:


1.  Solve the following differential equation \(e^y + 2x + (xe^y + 3y^2)y'=0\).

b.  \(e^{xy} + 2x + 3y = c\)

b.  \(xe^{y} + x^2 + y^3 = c\)

c.  \(e^{xy} + 2x + 3y^2 = c\)

d.  \(\frac{x^2}{2}e^{y} + 2x + 2y^3 = c\)

e.  This equation has no solution.

 

2.  Find an integratng factor \(\mu\) to make the equation \(3x^2y + 2xy + 2y^3 + (x^2 + 2y^2)y' = 0\) exact.

b.  \(\mu(x) = 3x^2y\)

b.  \(\mu(x) = 3\)

c.  \(\mu(x) = 3x\)

d.  \(\mu(x) = e^{3x}\)

e.  \(\mu(x) = 3^x\)

 

3.  Solve the differential equation \(y'' - y' - 2y = 0\).

b.  \(y(t) = c_1 e^t + c_2 e^{2t}\)

b.  \(y(t) = c_1 e^{-t} + c_2 e^{2t}\)

c.  \(y(t) = c_1 e^t + c_2 e^{-2t}\)

d.  \(y(t) = c_1 e^{-t} + c_2 e^{-2t}\)

e.  This equation has no solution.

 

4.   Write out and submit your solution for questions 1-3.

 

5.   Use the integrating factor you found in question 2 to solve the differential equation.