2020/7/11微积分--求导法则1几个初等函数的导数1.常数的导数:2.幂函数的导数:特殊:0c21,()2xxx2111(),()2xxxx0000()()()lim.xxfxfxfxxx000()()limxfxxfxx复习:导数概念1()xx2020/7/11微积分--求导法则23.对数函数的导数1(log)ln1(ln)axxaxx4.正、余弦函数的导数(sin)cos(cos)sinxxxx2020/7/11微积分--求导法则3一、和、差、积、商的求导法则定理(),(),(),uxvxxx如果函数在点处可导则它们的和、差、积、商分母不为零在点处也可导并且).0)(()()()()()(])()([)3();()()()(])()([)2();()(])()([)1(2xvxvxvxuxvxuxvxuxvxuxvxuxvxuxvxuxvxu3.2求导法则2020/7/11微积分--求导法则4证:0()()limxuuvvuvuvx()(2)[()()]()()()();uxvxuxvxuxvx0limxvuuvuvx000limlimlimxxxuvuvuvxxxuvuv=+5证0()()lim(())()xuvxuxvvxvvxx0()()()()()[]lim()xuxuuxuxvxvvxvxx2()()()()()(3)[](()0).()()uxuxvxuxvxvxvxvx0()()lim()()xuvvxuxxxvxxvx2)]([)()()()(xvxvxuxvxu2020/7/11微积分--求导法则6推论(2)[()]();CfxCfx1(3)[()]niifx11(1)[()]();nniiiifxfx12()()()nfxfxfx11()();nnikikkifxfx12()()()nfxfxfx12()()()nfxfxfx2020/7/11微积分--求导法则7例1223lncos.yxxx求+sin的导数2解4yx3x例2.ln2sin的导数求xxy解xxxylncossin2xxxylncoscos2xxxln)sin(sin2xxx1cossin2sinx.2sin1ln2cos2xxxx2020/7/11微积分--求导法则841sincos,2dd求11sincossinsincos22dd42248dd332cos4logsin7yxxxx223143sin3ln2yxxxx3lncosyxxx2233lncoscoslnsinyxxxxxxxx2020/7/11微积分--求导法则9例3.tan的导数求xy解)cossin()(tanxxxyxxxxx2cos)(cossincos)(sinxxx222cossincosxx22seccos1.sec)(tan2xx即.csc)(cot2xx同理可得2020/7/11微积分--求导法则10例4.sec的导数求xy解)cos1()(secxxyxx2cos)(cos.tansecxxxx2cossin.cotcsc)(cscxxx同理可得2020/7/11微积分--求导法则11三角函数求导公式sincosxxcossinxx2tansecxx2cotcscxxsecsectanxxxcsccsccotxxx(1)f不存在2(1),1()ln,1xxfxxx设()(1),(2)fxff求及例51()2,xfx时,11()xfxx时,解11()(1)2(1)ln1(1)limlim211xxfxfxfxx(1)21(2)2ff11()(1)lnln1(1)limlim11xxfxfxfxx11ln[1(1)]1limlim111xxxxxx即f(x)在x=1不可导2,1()1,1xfxxxx=1时:2020/7/11微积分--求导法则13定理()()0,(),yxxyIyyfxI如果函数在某区间内单调、可导且那末它的反函数在对应区间内也可导且有即反函数的导数等于直接函数导数的倒数.二、反函数的求导法则1()()fxy2020/7/11微积分--求导法则14证,xIx任取xx以增量给的单调性可知由)(xfy,0y,)(连续xf00xy时0)(y又知xyxfx0lim)(yxy1lim0)(1y.)(1)(yxf即),0(xIxxx2020/7/11微积分--求导法则15()xxee(0,1)xyaaay,求例7解logaxy在(0,+∞)内单调连续,值域(-∞,+∞)1(log)0(0,)lnayyya且,1()(log)xayay故其反函数xya在(,)内可导,且lnyalnxaa()ln(0,1)xxaaaaa即:特别地,2020/7/11微积分--求导法则16证:(arcsin)x2211(arcsin),(arccos)11xxxxcos0y1(sin)y1cosyarcsinyxsinxy22y222cos1sin1yyx211x2020/7/11微积分--求导法则17证:211x2211(arctan),(arccot)11xxxx(arctan)x1(tan)y21secyarctanyxtanxy22y222sec1tan1yyx0(sincos)xyexx()(sincos)()(sincos)xxyexxexx(sincos)(cossin)2cosxxxexxexxex2(3)(sin1)xyxax22(3)(sin1)(3)(sin1)xxyxaxxax2(23ln)(sin1)(3)cosxxxaaxxaxsin()1cosxxfxx2(sin)(1cos)sin(1cos)()(1cos)xxxxxxfxx222(sincos)(1cos)sinsin(1cos)1cosxxxxxxxxxx2020/7/11微积分--求导法则191(1)()0()()yfxfxfx,,且可导(2)lnln2xyxxxe(3)(sin2cos)xyexx3tan(4)3arctansinxyxxxx•练习:求下列函数的导数2020/7/11微积分--求导法则20小结(1)(u±v)′=u′±v′;(2)(uv)′=u′v+uv′;(3)(cu)′=cu′;(4)(u/v)′=(v≠0);注意:[()()]()();uxvxuxvx.)()(])()([xvxuxvxu分段函数求导时,不同表达式的分界点处用左右导数定义式求导.2uvuvv(5)反函数的导数等于直接函数导数的倒数1().()fxy2020/7/11微积分--求导法则21解答232xy令0y0322x321x322x切点为964,32964,32所求切线方程为964y964y和思考题求曲线上与轴平行的切线方程.32xxyx2020/7/11微积分--求导法则22作业:P1079、15、16(可不空行、正、反面做;自己对书后答案;有问题彩笔做记号)2020/7/11微积分--求导法则23•练习:求下列函数的导数;)(9sincos410)(1452xxxxf;)(0)(201121aaxaxaxaxgnnnn。)2()3(2xxy;)(xxxfcos7)(452020/7/1124例6).(,0),1ln(0,)(xfxxxxxf求设解,1)(xf,0时当x,0时当x0ln(1)ln(1)()limxxxxfxx01limln(1)1xxxx,11x01lim1xxxx,0时当x0()(0)(0)lim0xfxffx,100()(0)ln(1)ln(10)(0)limlim0xxfxfxfxx,1.1)0(f.0,110,1)(xxxxf0ln(10)lim0xxx2020/7/11微积分--求导法则25下课