已知\( {y^{(5)}} = \cos x \)，则\( {y^{(7)}}\left| {_{x = 0}} \right. \)为 .______
举一反三
- 已知\( y = {x^{\cos x}} \) ,则\( y' = \left( { - \sin x\ln x + { { \cos x} \over x}} \right){x^{\cos x}} \)( ).
- 设\(z = {e^u}\sin v,\;u = xy,\;v = x + y\)，则\( { { \partial z} \over {\partial y}}=\)( ) A: \(x{e^{xy}}\sin \left( {x + y} \right) + {e^{xy}}\cos \left( {x + y} \right)\) B: \(x{e^{xy}}\sin \left( {x + y} \right) \) C: \( {e^{xy}}\cos \left( {x + y} \right)\) D: \(x{e^{xy}}\sin \left( {x + y} \right) - {e^{xy}}\cos \left( {x + y} \right)\)
- 已知\( {y^{(5)}} = \sin x \)，则\( {y^{(7)}} = \cos x \)（ ）.
- 已知\( y = \ln (2{\rm{ + }}6x) \)，则\( y'\left| {_{x = 0}} \right. \)为 .______
- 设\(D = \left\{ {(x,y)\left| { { x^2} + {y^2} \le 9,x \ge 0,y \ge 0} \right.} \right\}\)，则\(\int\!\!\!\int\limits_D {(x + 3y)} d\sigma = \)______