公開課教案：指數(shù)函數(shù)(高三復(fù)習(xí)課)

2012學(xué)年度第一學(xué)期高三數(shù)學(xué)助學(xué)提綱1212ya（0a1）xxyy圖像xoxoO；）；；函數(shù)性質(zhì)；1(x)3f21xf(x)a1(aa．2x1(x)(af是Ra．x12012學(xué)年度第一學(xué)期高三數(shù)學(xué)助學(xué)提綱1(x)afa．41xf(x)32當(dāng)xx1y()3．xx3aa0a1且y數(shù)a（x5aa0a1y數(shù)a（且x2(x)aba0a1f（且）x0a1b0且0a1b0且a1b0且a1b0．且．．．4x123[0,xyx229(a4)340xaxx943a0xaxx94340xaaxx22012學(xué)年度第一學(xué)期高三數(shù)學(xué)助學(xué)提綱(x)a2b3a,b題fxxab0若ab0f(x)0f(xf(x)時⑵若abx1題2－.x2x|若x若20mt1f(xf(x)()212、x1(x2、、x、2x41.y）21x1,(,、、、、(x)(1a)af2xx32012學(xué)年度第一學(xué)期高三數(shù)學(xué)助學(xué)提綱0a1,b1yabx）|mxm()x1a．(2a1(,0)2x4k2k30xkxx．xxxx3x|1221．42m20xmxx11()1xfx42xx1已知指數(shù)函數(shù)()，當(dāng)(0,)，有1，解關(guān)于x的不等式y(tǒng)xxya(xx)。aa9k36(k0x[0,kxkf(x)在xx13x1x0()fx是R．912xf(x)(yy在f(x)1(x)f342012學(xué)年度第一學(xué)期高三數(shù)學(xué)助學(xué)提綱121ya(aax2ya（0a1）xxyy圖像xoxoOx；函數(shù)；1；；質(zhì)(x)3[)f21x1(x)a1(aa(．f2x1252012學(xué)年度第一學(xué)期高三數(shù)學(xué)助學(xué)提綱是Raa(x)(a．(1,2)fx112f(x)a．41x5f(x)32當(dāng)xx318()3．xx33aa0a1且y數(shù)a（x5125aa0a1y數(shù)a（且x212或2(x)aba0a1f（且）x0a1b0且0a1b0且a1b0且a1b0．且C．．．4x123[0,xyx21212tt,ytt3t4)5t4x2即解，22x22y5t8即x3y3．9(a4)340xaxx3t0tt(at40(0,)2在t（x(4)160a2t(a4)08at12tt40124(a34a8x3x943a0變式訓(xùn)練1：若關(guān)于x的方程有實數(shù)解，求實數(shù)a的取值范有實數(shù)解，求實數(shù)a的取值范xx圍a(,4]）94340變式訓(xùn)練2：若關(guān)于x的方程axx(圍a）(x)a2b3a,b題fxxab0。62012學(xué)年度第一學(xué)期高三數(shù)學(xué)助學(xué)提綱00f(x)⑴若ab⑵若abf(xf(x)時xb0,,當(dāng)axxRxx，2121(x)f(x)a2)b3)22,a0a2)0，1212則f∵xxxxxxxx12121233,b0b3)0f(x)f(x)0f(x)R在xxxx121212當(dāng)a在b0f(x)Rf(x1)f()a2b23⑵xx3aa2bbb0b0()x()()x()當(dāng)a當(dāng)a）xx2bb3a2a33aa2bb()x()()x()）．xx2bb3a2a3Ra0a1b0b1f(x)akbk，且，且xxa、a，b1ab1f(x)f(x)R在1b0k0a，1f(x)akaf(x)akaf(x)）由已知，bx是，即xxxa(x)f(x)akaaka(kaa)0fxxxxxx1f(x)f(x)f(x)是奇函數(shù)，則意實數(shù)x恒成立，所以k．若aka(aka)(kaa)0xxxxxxxk1．k1f(x)k1f(x)k1f(x)，10b1，yaybk0（2axxykb0f(x)在Rx設(shè)x、1且xRxx212f(x)f(x)akbakb(aa)kbb)xxxxxxxx221121212172012學(xué)年度第一學(xué)期高三數(shù)學(xué)助學(xué)提綱10b1xxk0，，aaf，，12a0kbb)0，，x2xxx121(x)f(x)0f(x)在R211題2－.x2x|若x若20mt1當(dāng)02－.x2x12－22xxxx2x2＋．x21t1當(dāng)22－＋2－．mtt2t4tt2t222，ttt故m．12f(xf(x)()D12、x1(x2、、x、2x41yD21x1,(,、、、、(x)(1a)af2Bxx0a1,b1yabAx2mxm()A|1x|－1(2a1(,0)，則實數(shù)a的取值范圍是不等式2的解集為x．(,1)(1,)4k2k30xxx82012學(xué)年度第一學(xué)期高三數(shù)學(xué)助學(xué)提綱．k(,xxxx3x|1221242m20xmxx1942m20m422(2)2m(2，xxxxx2411()1xfx42xx111232f(x)14212212,xx2xxx424xx14123,fx,≤2≤82x1()28∵x即x,∴即xxx43f(x)。1已知指數(shù)函數(shù)()，當(dāng)(0,)，有1，解關(guān)于x的不等式y(tǒng)xyxalog1)logx(6aa11解：∵()在(0,)時，有1，∴a1即1于是由yxyxaax16x(xx)6x0，aax10776，∴{|6}xxx229k36(k0x[0,kx1在kxx3030，x[0,t3xt[1,9]kk，936tt6xx121,60,8236ttk．423x1(x)x0()fxf是R．912xf(x)(yy在f(x)1(x)f3t10f(x)t30t1（yxx212t92012學(xué)年度第一學(xué)期高三數(shù)學(xué)助學(xué)提綱1121y2110()yfxfx(),有．122tt113x0f(x),0f(x)23x110x0，fxfx()()t3，0t1當(dāng)xx9123xt1t1t1tt322t322，2，，6t16t2121x13322f(x)22),)．33102012學(xué)年度第一學(xué)期高三數(shù)學(xué)助學(xué)提綱．k(,xxxx3x|1221242m20xmxx1942m20m422(2)2m(2，xxxxx2411()1xfx42xx111232f(x)14212212,xx2xxx424xx14123,fx,≤2≤82x1()28∵x即x,∴即xxx43f(x)。1已知指數(shù)函數(shù)()，當(dāng)(0,)，有1，解關(guān)于x的不等式y(tǒng)xyxalog1)logx(6aa11解：∵()在(0,)時，有1，∴a1即1于是由yxyxaax16x(xx)6x0，aax10776，∴{|6}xxx229k36(k0x[0,kx1在kxx3030，x[0,t3xt[1,9]kk，936tt6xx121,60,8236ttk．423x1(x)x0()fxf是R．912xf(x)(yy在f(x)1(x)f3t10f(x)t30t1（yxx212t92012學(xué)年度第一學(xué)期高