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Solution: The corresponding homogeneous equation is y''-2y'+y=0, the eigenequation is r 2-2r+1=0, there is a real root r=1, so the general solution of the homogeneous equation corresponding to the given equation is .
y=(c1+c2x)e^x
Since =0 is not the root of the eigenequation, we should let y*=b0x+b1, then b0x-2b0+b1=x,> b0=1,b1=2,> y*=x+2, and the general solution is y=(c1+c2x)e x+x+2
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Homogeneous characteristic equation: r 2-2+1=0
r1=r2=1
Its homogeneous general solution: y=(c1+c2x)e x
It is observed that y=x+2
Therefore its solution is y=(c1+c2x)e x+x +2
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First, find the solution of the homogeneous equation:
The characteristic equation is r -2r+1=0
r1=r2=1
The general solution of the homogeneous equation is y=e x(c1+c2x) and then find the special solution of the non-secondary equation:
The special solution form is y0=e ( x)·x k· (ax+b)p(x)=x=e ( x)·x
0 is not the root of the eigenequation.
k=0y0=e^(0x)·x^0·(ax+b)=ax+by′=a,y″=0
Bring in the original equation: 0-2a+ax+b=x
a=1,b=2
y0=x+2
The solution of the original equation is y=e x(c1+c2x)+x+2.
I hope my answer is helpful to you.
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Multiply both sides by e (x 2) and note (e (x 2) y).'=(y'+2xy)e^(x^2)
I get the points on both sides.
e^(x^2)y)=x^2+c
So y=x 2e (-x 2)+ce (-x 2).
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The characteristic equation a 2 +2a + 5 = 0 has a conjugated spine and a releasing beam seepage root -1+2i, -1-2i
Therefore, the general solution of slag destruction is y=e (-x) (c1cos2x+c2sin2x).
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Set y'=p, then y''=dp dy*dy dx=pdp dypdp dy=(1+p 2) 2y
2pdp/(1+p^2)=dy/y
ln(1+p^2)=ln|y|+ln|c|Get 1+p 2=cy
y'= Punch ruler (cy-1).
dy/√(cy-1)=dx
2 c (cy-1) = x+c'(c,c'The scatter height is constant).
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1) First, find the general solution of the homogeneous differential equation y''+3y'+2y=0:
The characteristic equation is r 2 + 3r + 2 = 0, and the solution is r1=-1, r2=-2, so the general solution of the homogeneous differential equation is y h=c 1e +c 2e (c 1 and c 2 are any constants of the honor line).
Next, find the special solution of the non-homogeneous differential equation y''+3y'+2y=3x+1:
Assuming that the special solution is y p=ax+b, substituting the original equation gives 2a+3a+2ax+2b=3x+1
Comparing the coefficients of the same power, we get 2a+3b=1, 2a=3, and the solution is a=3 2, b=-5 4
Therefore, the general solution of this non-homogeneous differential equation is y=c 1e +c 2e +3 2x-5 4
2) First, find the general solution of the homogeneous differential equation y''+y'=0:
The eigenequation is r 2 + r = 0, and the solution is r 1 = 0 and r 2 = -1, so the general solution of the homogeneous differential equation is y h=c 1 + c 2e (c 1 and c 2 are arbitrary constants).
Next, find the special solution of the non-homogeneous differential equation y''-5y'+y'=x:
First, find the general solution of the homogeneous differential equation y''-5y'+y'=0:
The characteristic equation is r 2-5r+1=0, and the solution is r1=(5+ 21) 2, r2=(5- 21) 2, so the general solution of the homogeneous differential equation is y h=c 1e +c 2e (c 1, c 2 are arbitrary constants).
Since the non-homogeneous term is a one-time function, we guess that its special solution is y p=ax+b, and substituting the original equation gives a+bx-5ax+2a=12x (21-21).
Comparing the coefficients of the same power, we get -a+2a=12 (21-21), 1-5a+b=0, and a=12 (21-21) 3, b=5a-1=-(11+ 21) (21-21).
Therefore, the general solution of this nonhomogeneous differential equation is y=c 1+c 2e +12 (21- 21)x-(11+ 21) (21- 21).
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y''/y'^2=2y/(y^2+1)(-1/y')'Dan = (ln(y 2+1)).'Integral chain light on both sides: -1 y'=ln(y 2+1)+c1-dx=(ln(y 2+1)+c1)dy: -x= ln(y 2+1)dy+c1y=yln(y 2+1)- y*2y (y 2+1)dy+c1y=yln(y 2+1)- 2y 2+2-1) (y 2+1)dy+c1y=yln(y 2+1)-
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Solution: The corresponding homogeneous equation is.
y''-2y'+y=0, and the characteristic equation is.
r 2-2r+1=0, there is a real root r=1, so the general solution of the homogeneous equation corresponding to the given equation is.
y=(c1+c2x)e^x
Since =0 is not the root of the eigenequation, y*=b0x+b1, then.
b0x-2b0+b1=x,=>
b0=1,b1=2,=>
y*=x+2, the general solution is .
y=(c1+c2x)e^x+x+2
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y"y'2y
xy"y'2y
According to the theory of differential equations, the general solution of (1) is the sum of a special solution of (1) and the general solution of (2).
1) Special solution: y
ax+b brings in (1) to solve a,b.
2) General solution: y*
c₁e^(s₁x)
c₂e^(s₂x)
s₁=2,s₂=-1.
1) General solution: y
y₁y*ax+b
c₁e^(s₁x)
c₂e^(s₂x)
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Homogeneous characteristic equation: r 2-2+1=0
r1=r2=1
Its homogeneous general solution: y=(c1+c2x)e x
It is observed that y=x+2
Therefore its solution is y=(c1+c2x)e x+x
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First, find the solution of the homogeneous equation:
The characteristic equation is r -2r+1=0
r1=r2=1
The general solution of the homogeneous equation is y=e x(c1+c2x) and then find the special solution of the non-secondary equation:
The special solution form is y0=e ( x)·x k· (ax+b)p(x)=x=e ( x)·x
0 is not the root of the eigenequation.
k=0∴y0=e^(0x)·x^0·(ax+b)=ax+b∴y′=a,y″=0
Bring in the original equation: 0-2a+ax+b=x
a=1,b=2
y0=x+2
The solution of the original equation is y=e x(c1+c2x)+x+2.
I hope my answer is helpful to you.
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dy/dx=2y/x
Just use the separation variable method.
dy/2y=dx/x
The integration of both sides yields: (lny) 2=lnx+c
lny=2lnx+2c
y=e^(2lnx+2c)=(e^2c)*e^(2lnx)=(e^2c)x^2
c is an arbitrary constant, so e 2c is a constant.
y=ax 2 is the general solution.
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In the ordinary differential equations of this course, the content of the specific solution of the equation is not the focus, and the real essence lies in the qualitative analysis, including existential uniqueness, stability, and so on. Because most of the equations cannot be solved analytically, but we still have to analyze the properties of the solutions when they cannot be solved concretely, which is the basic spirit of modern ordinary differential equation theory and partial differential equation theory. As for not understanding the lipschitz condition, I can only say that the foundation of the number of points is not solid enough, lipschitz is defined in the number of points continuously, and the uniqueness of the picard iteration proves that it does not go beyond the scope of the number of points. >>>More
Science Encyclopedia: Partial Differential Equations.