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Answer each of the following to the best of your ability. Show all necessary wor

ID: 2862171 • Letter: A

Question

Answer each of the following to the best of your ability. Show all necessary work and follow all instructions carefully. Use this sheet as a cover sheet and attach your work to the back of this sheet. Remember, I am testing you, not your calculator. Each question is worth 2 points. Good luck! Use separation of variables to solve the initial value problem: dy/dx = csc^2y/x^3, y(pi) = 0. show that the following differential equation is exact and then solve the equation: [2xsin(x^2) + 6xe^5y]dx + (15x^2e^5y + 15y^2) dy = 0. Use a linear substitution to solve the differential equation: dy/dx = (5x + y)^3 -5, y(1) =0, express your answer in "x = " form. Solve the linear differential equation (x+3dy/dx = 5x^2 - 2y Using an integrating factor. You may assume that x >0. Determine where dy/dx=x/y + x-sin(x/y)will have unique solutions.

Explanation / Answer

1) given

dy/dx =csc2y /x3

seperate the variables

dy/csc2y =x3 dx

sin2y dy=x3 dx

(1/2)(1-cos2y) dy=x3 dx

integrate on both sides

(1/2)(1-cos2y) dy=x3 dx

(1/2)(y-(1/2)sin2y)=(1/4)x4 +c

y-(1/2)sin2y=(1/2)x4 +c

given y()=0

0 -0 =(1/2)4 +c

c=-(1/2)4

y-(1/2)sin2y=(1/2)x4 -(1/2)4 is the particular solution