
§4 導(dǎo)數(shù)的四則運(yùn)算法則新知初探·課前預(yù)習(xí)題型探究·課堂解透新知初探·課前預(yù)習(xí)[教材要點(diǎn)]要點(diǎn) 導(dǎo)數(shù)的運(yùn)算法則若函數(shù)f(x),g(x)均為可導(dǎo)函數(shù),則有狀元隨筆 法則1:函數(shù)的和(差)的導(dǎo)數(shù)導(dǎo)數(shù)的加法與減法法則,可由兩個(gè)可導(dǎo)函數(shù)推廣到任意有限個(gè)可導(dǎo)函數(shù)的情形(一般化),即[u(x)±v(x)±…±w(x)]′=u ′(x)±v ′(x)±…±w ′(x).法則2:函數(shù)的積的導(dǎo)數(shù)(1)(特殊化)當(dāng)g(x)=c(c為常數(shù))時(shí),法則2可簡(jiǎn)化為[cf(x)]′=c f ′(x)+c[f(x)]′=0+cf ′(x)=cf ′(x),即 [cf(x)]′=cf ′(x).(2)由上述結(jié)論及法則1可得[af(x)+bg(x)]′=af ′(x)+bg ′(x),其中a,b為常數(shù).(3)函數(shù)的積的導(dǎo)數(shù)可以推廣到有限個(gè)函數(shù)的乘積的導(dǎo)數(shù),即[u(x)v(x)×…×w(x)]′=u ′(x)v(x)×…×w(x)+u(x)v ′(x)×…×w(x)+…+u(x)v(x)×…×w ′(x).??√×√×2.已知函數(shù)f(x)=cos x+ln x,則f′(1)的值為( )A.1-sin 1 B.1+sin 1C.sin 1-1 D.-sin 1答案:A?3.函數(shù)y=sin x·cos x的導(dǎo)數(shù)是( )A.y′=cos2x+sin2x B.y′=cos2x-sin2xC.y′=2cos x·sin x D.y′=cos x·sin x答案:B解析:y′=(sin x·cos x)′=cos x·cos x+sin x·(-sin x)=cos2x-sin2x.故選B.4.若f(x)=(2x+a)2,且f′(2)=20,則a=________.1解析:f(x)=4x2+4ax+a2,∵f′(x)=8x+4a,∴f′(2)=16+4a=20,∴a=1.題型探究·課堂解透??方法歸納利用導(dǎo)數(shù)的公式及運(yùn)算法則求導(dǎo)的思路?答案:BC?????變式探究1 本例條件不變,求該切線到直線ax+2y+1=0的距離.?變式探究2 本例條件不變,求與直線y=-x平行且與曲線相切的直線方程.?方法歸納關(guān)于函數(shù)導(dǎo)數(shù)的應(yīng)用及其解決方法?01?????【易錯(cuò)警示】?答案:C?2.函數(shù)y=2x(ln x+1)在x=1處的切線方程為( )A.y=4x+2 B.y=2x-4C.y=4x-2 D.y=2x+4答案:C??答案:ABC?4.已知函數(shù)f(x)的導(dǎo)函數(shù)為f′(x),且滿足關(guān)系式f(x)=x2+3xf′(2),則f′(2)的值等于________.-2解析:由f(x)=x2+3xf′(2),得f′(x)=2x+3f′(2),令x=2,則f′(2)=4+3f′(2),解得f′(2)=-2.5.已知函數(shù)f(x)=x3+x-16 (1)求f′(x);(2)求曲線y=f(x)在點(diǎn)(2,-6)處的切線的方程.?
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