全微分:dz??z?z?u?u?udx?dy du?dx?dy?dz?x?y?x?y?z全微分的近似计算:?z?dz?fx(x,y)?x?fy(x,y)?y多元复合函数的求导法:dz?z?u?z?vz?f[u(t),v(t)] ???? dt?u?t?v?t?z?z?u?z?vz?f[u(x,y),v(x,y)] ? ????x?u?x?v?x当u?u(x,y),v?v(x,y)时,du??u?u?v?vdx?dy dv?dx?dy ?x?y?x?y隐函数的求导公式:FxFFdydyd2y??隐函数F(x,y)?0, ??, 2?(?x)+(?x)?dxFy?xFy?yFydxdxFyF?z?z隐函数F(x,y,z)?0, ??x, ???xFz?yFz
?F?F(x,y,u,v)?0?(F,G)?u隐函数方程组: J????G?(u,v)?G(x,y,u,v)?0?u?u1?(F,G)?v1?(F,G)??? ????xJ?(x,v)?xJ?(u,x)?u1?(F,G)?v1?(F,G)??? ????yJ?(y,v)?yJ?(u,y)微分法在几何上的应用:
?F?v?Fu?GGu?vFvGv
?x??(t)x?xy?y0z?z0?空间曲线?y??(t)在点M(x0,y0,z0)处的切线方程:0?????(t)?(t)??(t0)00?z??(t)?在点M处的法平面方程:??(t0)(x?x0)???(t0)(y?y0)???(t0)(z?z0)?0??FyFzFzFxFx?F(x,y,z)?0若空间曲线方程为:,则切向量T?{,,?GGGxGx?yzGz?G(x,y,z)?0曲面F(x,y,z)?0上一点M(x0,y0,z0),则:?1、过此点的法向量:n?{Fx(x0,y0,z0),Fy(x0,y0,z0),Fz(x0,y0,z0)}x?x0y?y0z?z03、过此点的法线方程:??Fx(x0,y0,z0)Fy(x0,y0,z0)Fz(x0,y0,z0)方向导数与梯度:
Fy}Gy2、过此点的切平面方程:Fx(x0,y0,z0)(x?x0)?Fy(x0,y0,z0)(y?y0)?Fz(x0,y0,z0)(z?z0)?0
?f?f?f函数z?f(x,y)在一点p(x,y)沿任一方向l的方向导数为:?cos??sin??l?x?y其中?为x轴到方向l的转角。?f??f?i?j?x?y???f??它与方向导数的关系是:?gradf(x,y)?e,其中e?cos??i?sin??j,为l方向上的?l单位向量。?f?是gradf(x,y)在l上的投影。?l函数z?f(x,y)在一点p(x,y)的梯度:gradf(x,y)?多元函数的极值及其求法:
设fx(x0,y0)?fy(x0,y0)?0,令:fxx(x0,y0)?A, fxy(x0,y0)?B, fyy(x0,y0)?C??A?0,(x0,y0)为极大值2AC?B?0时,???A?0,(x0,y0)为极小值??2则:值?AC?B?0时, 无极?AC?B2?0时, 不确定???重积分及其应用:
??f(x,y)dxdy???f(rcos?,rsin?)rdrd?DD?曲面z?f(x,y)的面积A???D??z???z??1?????dxdy????x???y?22平面薄片的重心:x?Mx?M??x?(x,y)d?D???(x,y)d?DD, y?MyM???y?(x,y)d?D???(x,y)d?DD平面薄片的转动惯量:对于x轴Ix???y2?(x,y)d?, 对于y轴Iy???x2?(x,y)d?平面薄片(位于xoy平面)对z轴上质点M(0,0,a),(a?0)的引力:F?{Fx,Fy,Fz},其中:Fx?f??D?(x,y)xd?(x?y?a)2222, Fy?f??3D?(x,y)yd?(x?y?a)2222, Fz??fa??3D?(x,y)xd?(x?y?a)22322柱面坐标和球面坐标:
?x?rcos??柱面坐标:f(x,y,z)dxdydz????F(r,?,z)rdrd?dz,?y?rsin?, ??????z?z?其中:F(r,?,z)?f(rcos?,rsin?,z)?x?rsin?cos??2球面坐标:?y?rsin?sin?, dv?rd??rsin??d??dr?rsin?drd?d??z?rcos??2??r(?,?)???f(x,y,z)dxdydz????F(r,?,?)r??2sin?drd?d???d??d?00?F(r,?,?)r02sin?dr重心:x?1M???x?dv, y???1M???y?dv, z???1M???z?dv, 其中M?x?????dv???转动惯量:Ix????(y2?z2)?dv, Iy????(x2?z2)?dv, Iz????(x2?y2)?dv曲线积分:
第一类曲线积分(对弧长的曲线积分):?x??(t)设f(x,y)在L上连续,L的参数方程为:, (??t??),则:?y??(t)??L?x?tf(x,y)ds??f[?(t),?(t)]??2(t)???2(t)dt (???) 特殊情况:??y??(t)??
第二类曲线积分(对坐标的曲线积分):?x??(t)设L的参数方程为,则:?y??(t)???P(x,y)dx?Q(x,y)dy???{P[?(t),?(t)]??(t)?Q[?(t),?(t)]??(t)}dtL两类曲线积分之间的关系:?Pdx?Qdy??(Pcos??Qcos?)ds,其中?和?分别为LLL上积分起止点处切向量的方向角。?Q?P?Q?P格林公式:(?)dxdy?Pdx?Qdy格林公式:(?)dxdy??Pdx?Qdy??????x?y?x?yDLDL?Q?P1当P??y,Q?x,即:??2时,得到D的面积:A???dxdy??xdy?ydx?x?y2LD·平面上曲线积分与路径无关的条件:1、G是一个单连通区域;2、P(x,y),Q(x,y)在G内具有一阶连续偏导数,且减去对此奇点的积分,注意方向相反!·二元函数的全微分求积:?Q?P在=时,Pdx?Qdy才是二元函数u(x,y)的全微分,其中:?x?y(x,y)?Q?P=。注意奇点,如(0,0),应?x?yu(x,y)?(x0,y0)?P(x,y)dx?Q(x,y)dy,通常设x0?y0?0。
曲面积分:
22对面积的曲面积分:f(x,y,z)ds?f[x,y,z(x,y)]1?z(x,y)?z(x,y)dxdyxy?????Dxy对坐标的曲面积分:,其中:??P(x,y,z)dydz?Q(x,y,z)dzdx?R(x,y,z)dxdy?号;??R(x,y,z)dxdy????R[x,y,z(x,y)]dxdy,取曲面的上侧时取正?Dxy号;??P(x,y,z)dydz????P[x(y,z),y,z]dydz,取曲面的前侧时取正?Dyz号。??Q(x,y,z)dzdx????Q[x,y(z,x),z]dzdx,取曲面的右侧时取正?Dzx两类曲面积分之间的关系:??Pdydz?Qdzdx?Rdxdy???(Pcos??Qcos??Rcos?)ds??高斯公式:
???(??P?Q?R??)dv???Pdydz?Qdzdx?Rdxdy???(Pcos??Qcos??Rcos?)ds?x?y?z??高斯公式的物理意义——通量与散度:??P?Q?R?散度:div????,即:单位体积内所产生的流体质量,若div??0,则为消失...?x?y?z??通量:??A?nds???Ands???(Pcos??Qcos??Rcos?)ds,?因此,高斯公式又可写成:???divAdv???Ands?????斯托克斯公式——曲线积分与曲面积分的关系:
??(??R?Q?P?R?Q?P?)dydz?(?)dzdx?(?)dxdy??Pdx?Qdy?Rdz?y?z?z?x?x?y?cos???yQcos???zR
dydzdzdxdxdycos?????上式左端又可写成:??????x?y?z?x??PQRP?R?Q?P?R?Q?P空间曲线积分与路径无关的条件:?, ?, ??y?z?z?x?x?yijk????旋度:rotA??x?y?zPQR???向量场A沿有向闭曲线?的环流量:Pdx?Qdy?Rdz?A???tds??常数项级数:
1?qn等比数列:1?q?q???q?1?q(n?1)n等差数列:1?2?3???n?
2111调和级数:1?????是发散的23n2n?1级数审敛法: