y-x^2,x=y^2绕y轴的体积-搜答案-智慧作业帮

y'-2y=x的通解

2/x+2/y=根号24(2y+2x)/xy=2√6x+y=xy√6x/y(x-y)-y/x(x-y)=1/(x-y)[(x/y-y/x)]=1/(x-y)[(x²-y²)/xy]

你的题目有点问题我这样做了x/{y(x-y)}-y/{x(x-y)}=（x平方-y平方）/{xy(x-y)}=(x+y)/xy2/x+2/y=2(x+y)/xy=根号24

[2x的平方-(x+y)(x-y)][(-x-y)(y-x)+2y的平方]=[2x²-(x²-y²)][(x+y)(x-y)+2y²]=(2x²-x&

求微分方程(2x-y²)y'=2y的通解由原式得：(2x-y²)dy=2ydx,即有2ydx+(y²-2x)dy=0.(1)P=2y,Q=y²-2x；ͦ

y''-2y'+y=e^-x的通解

特征方程r^-2r+1=0r=1(二重根)所以齐次通解是y=(C1x+C2)e^x设特解是y=ae^(-x)y'=-ae^(-x)y''=ae^(-x)代入原方程得ae^(-x)+2ae^(-x)+a

y''+2y'+y=x的通解

∵齐次方程y"+2y'+y=0的特征方程是r^2+2r+1=0,则r=-1（二重根）∴此齐次方程的通解是y=(C1x+C2)e^(-x)(C1,C2是常数)∵设原方程的解为y=Ax+B代入原方程,得A

y'-2y=(e^x)-x

首先求齐次方程通y'-2y=0特征方程：x-2=0x=2为特征根∴y=Ce^(2x)设方程的一个特解为y=Ae^x+ax+b代入方程：Ae^x+a-2Ae^x-2ax-2b=-Ae^x-2ax+a-2

(x-y)(z+y-x+y+2y)÷4y=(x-y)(z-x+4y)÷4y{(x+y)(x-y)-(x-y)的2次方+2y(x-y)}除以4y=(x-y)(x+y-x+y+2y)÷4y=(x-y)(4

y(x+y)+(x+y)(x-y)-x的2次方,其中X=-2,y=2分之一y(x+y)+(x+y)(x-y)-x的2次方=(x+y)(y+x-y)-x=x(x+y)-x=x(x+y-1)=-2*(-2

X+Y分之X-Y等于3x=-2yX+Y分之2(x-y)减X+Y分之3X+Y=(-x-3y)/(x+y)=1

因为(x-y)/(x+y)=3,则(x＋y)/(x－y)＝1/3则5(x-y)(x+y)-(x+y)/2(x-y)＝5*3-1/(3*2)=15-1/6=89/6

先一个一个的展开括号项,再同项合并就行了啊[x(x-y)-y(x-y)+(x+y)(x-y)]÷2x=[xx-xy-(xy-yy)+x(x-y)+y(x-y)]÷2x=[xx-xy-xy+yy+xx-

即(x-2y)²=0x-2y=0所以x=2y所以原式=(2x²+2xy-xy-y²)/(4x²-4xy+y²)=(2x²+xy-y²

y'+2y/x=x通解

解(x-y)(x+y)-(x-2y)²+x(3x-5y)-(x-y)(x-2y)=(x²-y²)-(x²-4xy+4y²)+(3x²-5xy

x+y/y=11/8说明11y=8（x+y）即8x=3y所以x-y/x+2y=3（x-y）/3(x+2y)=（3x-3y）/(3x+6y)=(3x-8x)/(3x+16x)=-5/19

这样解设y'=dy/dx=t,y''=d2y/dx2=dt/dx,带入得到t'(x+t^2)=t这样可以化成恰当方程dt=dx/t-x/t^2*dt=d(x/t)解得y'=t=(自己会算吧~)再积分一

原式化简=x＋2y=2011