(x方 y方)dx-xydy=0-搜答案-大师作文网

(x^2+y^2)dx-xydy=0dy/dx=(x²+y²)/(xy)dy/dx=((x/y)²+1)/(x/y)令u=y/x则dy=du*x+dx*udy/dx=(d

你未学过导数?d(x^3/3)/dx=1/3*3x^2=x^2相反就是积分过程d(xy^2)/dx=y^2*dx/dx+x*d(y^2)/dx=y^2+2xy*dy/dx=y^2dx+2xydy

先对方程进行处理,化成dy/dx=(1+y^2)/(xy(1+x^2))

u+xu'=u^2/(u-1)移向先xu'=u^2/(u-1)-u通分xu'=u^2/(u-1)-u(u-1)/(u-1)=(u^2-u^2+u)/(u-1)=u/(u-1)

这是一阶齐次微分方程(x^2+y^2)dx-xydy=0dy/dx=(x²+y²)/(xy)dy/dx=((x/y)²+1)/(x/y)令u=y/x则dy=du*x+dx

(x-2y^2)dx+2xydy=0M=x-2y^2N=2xyM_y=-4yN_x=2y(M_y-N_x)/N=-6y/2xy=-3/x假设有关于x的积分因子u(Mu)_y=(Nu)_xM_y*u=N

设u=y/xdy/dx=(x+y²)/xyu+xdu/dx=1/xu+uudu=1/x²dx1/2u²=-1/x+Cy²=2Cx²-2x希望能帮道楼主

整理有dy/dx=y^2/(xy-x^2)=(y/x)^2/[(y/x)-1]令y/x=u,y=ux,y'=u+xu'则原微分方程可化为u+xu'=u^2/(u-1)xu'=u/(u-1)(u-1)/

圆x²＋y²＋Dx＋Ey＋F=0与x轴相切,则圆心到x轴的距离等于圆的半径,则：|－E/2|=(1/2)√(D²＋E²－4F)E²=D²＋E

应该是可分离变量的吧两端同除以x^2得（1+(y/x)^2)dx=2y/xdy令y/x=uy=uxy'=u'x+u上式变为(1+u^2)=2u(u'x+u)整　理1+u^2=2u^2+2uu'x1-u

方程变形为dy/dx=x/y+y/x.令u=y/x,则y=xu,dy/dx=u++x*du/dx,所以原方程化为u+x*du/dx=u+1/u.所以udu=dx/x.两边积分1/2*u^2=lnx+l

由(x^2+y^2)dx-2xydy=0得到dy/dx=(x^2+y^2)/2xy=0.5(x/y+y/x)设y/x=z,则y=zxdy/dx=xdz/dx+z=0.5(1/z+z)化为zdz/(1-

y²+x²dy/dx=xydy/dxy'=y²/(xy-x²)x'=(x/y)-(x/y)²令x/y=u,x=yux'=u+yu'u+yu'=u-u&

设P(x,y)＝x^2＋y^2,Q(x,y)＝2xy,则αP/αy＝αQ/αx,所以此微分方程是全微分方程（x^2+y^2)dx+2xydy=0x^2dx＋(y^2dx+2xydy)＝0d(x^3/3

都是非线性非齐次微分方程

x^2+y^2+dx+ey+f=0(x+d/2)^2+(y+e/2)^2=1/4(d^2+e^2)-f当1/4(d^2+e^2)-f＞0时,表示以（-d/2,e/2)为圆心,在√[1/4(d^2+e^

原式两边乘以x^2得x^2e^xdx+3x^2y^2dx+2x^3ydy=0x^2e^xdx+dx^3y^2=0x^2e^xdx=-dx^3y^2两边积分得∫x^2e^xdx=-∫dx^3y^2x^2

这是一阶齐次微分方程(x^2+y^2)dx-xydy=0dy/dx=(x²+y²)/(xy)dy/dx=((x/y)²+1)/(x/y)令u=y/x则dy=du*x+dx