• 2021-04-14
    z=ysin(x+y)在点(1,0)的全微分为
  • cos1dx+(sin1+cos1)dy

    内容

    • 0

      如下命令中不能实现如下微分方程组[img=327x203]17e443a5d83ce02.png[/img],在初值条件[img=172x112]17e443a5e2ead01.png[/img]下的特解求解的是: A: [x,y] = dsolve('Dx+5*x+y = exp(t)', 'Dy-x-3*y=0', 'x(0)=1', 'y(0)=0', 't') B: [x,y] = dsolve('Dx+5*x+y = exp(t)', 'Dy-x-3*y=0', 'x(0)=1, y(0)=0', 't') C: [x,y] = dsolve('Dx+5*x+y = exp(t)', 'Dy-x-3*y=0', 'x(0)=1', 'y(0)=0') D: [x,y] = dsolve('Dx+5*x+y = exp(t)', 'Dy-x-3*y=0', 'x(0)=1', 'y(0)=0', 'x')

    • 1

      如果函数z=f(x,y)在点(x,y)的偏导数定存在, 则该函数在点(x,y)存在全微分

    • 2

      设\(f\left( {x,y,z} \right) = x{y^2} + y{z^2} + z{x^2}\),则\({f_{yz}}\left( {0,-1,0} \right) = \)( ) A: 1 B: 0 C: -1 D: 2

    • 3

      int x=1,y=2,z; z=(x!=y)? x+y : x;则z= ________ 。

    • 4

      已知点A(x,1),B(1,0),C(0,y),D(-1,1),若,则x+y等于 A: 1 B: 2 C: 3 D: 4