下列方程中,不是全微分方程的为( )。
A: \(\left( {3{x^2} + 6x{y^2}} \right)dx + \left( {6{x^2}y + 4{y^2}} \right)dy = 0\)
B: \({e^y}dx + \left( {x \cdot {e^y} - 2y} \right)dy = 0\)
C: \(y\left( {x - 2y} \right)dx - {x^2}dy = 0\)
D: \(\left( { { x^2} - y} \right)dx - xdy = 0\)
A: \(\left( {3{x^2} + 6x{y^2}} \right)dx + \left( {6{x^2}y + 4{y^2}} \right)dy = 0\)
B: \({e^y}dx + \left( {x \cdot {e^y} - 2y} \right)dy = 0\)
C: \(y\left( {x - 2y} \right)dx - {x^2}dy = 0\)
D: \(\left( { { x^2} - y} \right)dx - xdy = 0\)
举一反三
- 由\( y = {x^2} - 1,\;y = 0 \)围成的平面图形面积可表示为( )。 A: \( \int_{ - 1}^1 {\left( { - {x^2} + 1} \right)} dx \) B: \( \int_{ - 1}^1 {\left( { { x^2} - 1} \right)} dx \) C: \( \int_0^1 {\left( { - {x^2} + 1} \right)} dx \) D: \( \int_0^1 {\left( { { x^2} - 1} \right)} dx \)
- 下列方程中是线性微分方程的是( )。 A: \( \cos \left( {y'} \right) + {e^y} = x \) B: \( xy'' + 2y' - {x^2}y = {e^x} \) C: \( {\left( {y'} \right)^2} + 5y = 0 \) D: \( y'' + \sin y = 8x \)
- 函数\(z = {\left( {xy} \right)^x}\)的全微分为 A: \(dz = \left( { { {\left( {xy} \right)}^x} + \ln xy} \right)dx + x{\left( {xy} \right)^x}dy\) B: \(dz = \left( { { {\left( {xy} \right)}^x} + \ln xy} \right)dx + { { x { { \left( {xy} \right)}^x}} \over y}dy\) C: \(dz = {\left( {xy} \right)^x}\ln xydx + { { x { { \left( {xy} \right)}^x}} \over y}dy\) D: \(dz = {\left( {xy} \right)^x}\left( {1 + \ln xy} \right)dx + { { x { { \left( {xy} \right)}^x}} \over y}dy\)
- 下列函数中( )不是方程\( y' + xy = 0 \)的解。 A: \( y = {e^{ - { { {x^2}} \over 2}}} \) B: \( \ln \left| y \right| = - { { {x^2}} \over 2} \) C: \( y = {e^{ - { { {x^2}} \over 2}}} + 2 \) D: \( \ln \left| y \right| = - { { {x^2}} \over 2} +2\)
- 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