ysinx=ylny,y x=x 2=e
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(一题)从这步d(ysinx)-dcos(x-y)=0到这步sinxdy+ycosxdx+sin(x-y)(dx-dy)=0不懂是么?ysinx是两个数相乘,对它d(ysinx)时就得用公式d(UV)
两边关于x求一阶导y'*e^(x+y)-y'sinx-ycosx=0y'=ycosx/(e^(x+y)-sinx)
2x+yx2-2xy+y2•(x-y)=2x+y(x-y)2•(x-y)(2分)=2x+yx-y;(4分)当x-3y=0时,x=3y;(6分)原式=6y+y3y-y=7y2y=72.(8分)
设y=y(x)由方程ysinx=cos(x-y)所确定,则y'(0)=x=0时cos(-y)=cosy=0,故y=π/2+2kπ,k∈ZF(x,y)=ysinx-cos(x-y)=0dy/dx=-(&
变量分离dy/(ylny)=dxd(lny)/lny=dx(lny)^2/2=x+c
dy/ylny=dx/x两边积分得lnlny=lnx+C1lny=C2e^x再问:后面那题呢?再答:y=x(-1≤x≤1)再问:cosxsinydy=cosysinxdx,Y|(x=0)=45°求初始
参考答案:停车坐爱枫林晚,霜叶红于二月花.
两边对x求导:dy/dxsinx+ycosx-sin(x-y)(1-dy/dx)=0,将x=π/2带入已知方程得到y,再把x、y带入上式求得结果再问:x=π/2带入已知方程得到y。。。我算不出这个y
symsxy[xy]=solve('x*3012=x*1406+y*1753+202480','x+y=10000')这是求xy的临界值!
∵ylnydx+(x-lny)dy=0∴ylnydx/dy+x=lny.(1)∴原方程与方程(1)同解用常数变易法求解方程(1)∵ylnydx/dy+x=0==>dx/x=-dy/(ylny)==>d
这很简单啊y'sinx=ylnydy/(ylny)=sinxdxd(lny)/lny=sinxdx两边积分得到ln(lny)=-cosx+C,C是任意常数
xy+yx=10x+y+10y+x=11x+11y=100+x10x=100-11yx=10-1.1y所以y只能是0
应用复合函数求导方法,y′sinx+ycosx+(1+y′)sin(x+y)=0,(sinx+sin(x+y))y′+ycosx+sin(x+y)=0,y′=-(ycosx+sin(x+y))/(si
两边对x求导y'*sinx+ycosx-[-sin(x+y)*(1+y')]=0y'(sinx+sin(x+y))=y(1-cosx)y'=[1-cosx]/[sinx+sin(x+y)]0/0所以需
可分离变量型,原微分方程可化为dx/(1+x^2)=dy/(ylny),两边同时积分J1/(1+x^2)dx=J1/(lny)d(lny),得lnlny=arctanx+C1得通解lny=Ce^(ar
两边同时对y积分得d(yy')=d(0.5y^2(lny-0.5))y'=0.5ylny-1/4y+c1/y积分得y=1/4y^2lny-1/4y^2+C1lny+C2
数列1/1*2+1/2*3+…+1/n(n+1)的sn=1-1/2+1/2-1/3+----+1/n-1/(n+1)=1-1/(n+1)1-1/(n+1)中的1-是怎么得出的?1/n-的n取1吗,你不
即(10x+y)*(10y+x)=2268101xy+10x²+10y²=2268因为后面的10x²+10y²只可能是整十的数,所以2268中的个位8要靠101
若y=1,则原方程成立.若y≠1,则dy/(ylny)=dx/x^2两边积分:ln|lny|=-1/x+C|lny|=e^(-1/x+C)lny=±e^(-1/x+C)y=e^(±e^(-1/x+C)