Tugas Soal Dan Pembahasan Persamaan Differensial Eksak [PDF]

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Irang maulana



Soal dan pembahasan persamaan differensial eksak



1. ( x + 2y ) dx + ( 4y + 2x ) dy = 0







F(x,y)



=∫ (



)



= ∫(



( ) )



( )



= 2y2 + 2xy + Q(x) = 2y + Q’(x) x + 2y = 2y + Q’(x) Q’(x)



=x



Q(x)



=∫ = x2



F(x,y) = x2 + 2xy + 2y2 



F(x,y)



=∫



(



)



= ∫(



( ) )



= x2 + 2xy + Q(y) = 2x + Q’(y) 4y + 2x = 2x + Q’(y) Q’(y)



= 4y



Q(y)



=∫ = 2y2



F(x,y) = x2 + 2xy + 2y2



( )



Irang maulana



2. ( x2 + y ) dx + ( 2y2 + x ) dy = 0







F(x,y)



(



=∫



)



= ∫(



( ) )



( )



= x3 + xy + Q(y) = x + Q’(y) 2y2 + x = x + Q’(y) Q’(y)



= 2y2



Q(y)



=∫ =



y3



F(x,y) = x3 + xy + y3 



F(x,y)



=∫ ( = ∫(



)



( ) )



= y3 + xy + Q(x) = y + Q’(x) x2 + y = y + Q’(x) Q’(x)



= x2



Q(x)



=∫ = x2



F(x,y) = x3 + xy + y3



( )



Irang maulana



3. ( 2x + 2y ) dx + ( y3 + 2x ) dy = 0







F(x,y)



(



=∫



)



= ∫(



( ) )



( )



= x2 + 2xy + Q(y) = 2x + Q’(y) y3 + 2x = 2x + Q’(y) Q’(y)



= y3



Q(y)



=∫ =



y4



F(x,y) = x2 + 2xy + y4 



F(x,y)



=∫ (



)



= ∫(



( ) )



= y4+ 2xy + Q(x) = 2y + Q’(x) 2x + 2y = 2y + Q’(x) Q’(x)



= 2x



Q(x)



=∫ = x2



F(x,y) = x2 + 2xy + y4



( )



Irang maulana



Soal dan pembahasan Faktor integrasi 1. Y dx + ( y + 2x ) dy = 0 -



=1



-



=2 F(y)



=(



)



=(



)



=U



=







= =y U(x,y)M(x,y)dx + U(x,y)N(x,y)dy = 0 y (y) dx + y(y +2x)dy = 0 y2 dx + (y2 + 2xy) dy = 0 (eksak)



Irang maulana



2. 2y dx + x dy = 0 -



=2



-



=1 F(y)



=( =(



) )



= U



=







= =x U(x,y)M(x,y)dx + U(x,y)N(x,y)dy = 0 x (2y) dx + x(x)dy = 0 2xy dx + x2 dy = 0 (eksak)