Find the general solution of differential equations. y'' + y' -

quiquenobi2v6

quiquenobi2v6

Answered question

2021-12-28

Find the general solution of differential equations.
y+y2y=ex+4sinx+x2x

Answer & Explanation

Serita Dewitt

Serita Dewitt

Beginner2021-12-29Added 41 answers

Step 1
The given differential equation is
y+y2y=ex+4sinx+x2x
To find the solution, CF and PI calculated
Step 2
The auxilary equation can be written as
m2+m2=0
m2+2mm2=0
m(m+2)1(m+2)=0
(m+2)(m1)=0
m=2,1
Complementry function
CF=C1em,x+c2em2x
CF=C1ex+C2e2x
Step 3
To find particular integration
PI=iD2+D2ex+4D2+D2sinx+1D2+D2(x2x)
=x.iex2D+1+412+D2sinx+12[1D2D22](x2x)
=x.ex2×1+1+4D3sinx12(1D2D22)1(x2x)
=x.ex3+4(D+3)D29sinx12[1+(D2+D22)+(1)(2)2(D+D22)2][x2x]
Heather Fulton

Heather Fulton

Beginner2021-12-30Added 31 answers

For the equation y+y2y=ex+4sinx+x2x, the characteristic polynomium is m2+m2=(m1)(m+2)=0. Roots 1 , - 2. The solution to the homogeneous part of the equation is yh=C1ex+C2e2x. For the paticular integral we use the method of undetermined coefficients. Try yp=Axex+Bsinx+Ccosx+Dx2+Ex+F. Substituting in the equation and collecting terms obtain A=13,B=65,C=25,D=12,E=0,F=12. Then the solution is y=C1ex+C2e2x+(13)xex(65)sinx(25)cosx(12)(x2+1).
karton

karton

Expert2022-01-10Added 613 answers

Solve (d2y(x))/(dx2)+(dy(x))/(dx)2y(x)=ex+x2x+4sin(x):
Apply the Laplace transformation Lx[f(x)](s)=integral0f(x)esxdx to both sides:
Lx[(d2y(x))/(dx2)+(dy(x))/(dx)2y(x)](s)=Lx[ex+x2x+4sin(x)](s)
Evaluate Laplace transforms:
(s2+s2)(Lx[y(x)](s))(s+1)y(0)y(0)=1/s2+2/s3+1/(s1)+4/(s2+1)
Solve for Lx[y(x)](s):
Lx[y(x)](s)=(1/s2+2/s3+1/(s1)+4/(s2+1)+y(0)(s+1)+y(0))/(s2+s2)
Decompose Lx[y(x)](s) via partial fractions:
Lx[y(x)](s)=1/(3(s1)2)+8/(9(s1))1/s31/(2s)+1/(90(s+2))6/(5(s2+1))(2s)/(5(s2+1))+(2y(0))/(3(s1))+y(0)/(3(s+2))+(y(0))/(3(s1))(y(0))/(3(s+2))
Take the inverse Laplace transform of both sides:
y(x)=(8ex)/9+e2x/90x2/2+(exx)/3(2cos(x))/5(6sin(x))/5+(2c1ex)/3+1/3c1e2x+(c2ex)/31/3c2e2x1/2
Simplify the arbitrary constants:
Answer:

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