2020届高考数学选择题填空题专项练习(文理通用)09 分段函数02

第I卷（选择题)51,x0x2020·f(x)(a)2af）2,x0x．(,2)．(1,2)．(0,3)．(Aa0和a0.212a00<a<3a12(a0a.212aa.,1axxxxfxa4xx1122fxfx0a）12xx121,．4,8．．．Dfxfxfx是012Rxx12aa的.,1axxfxfxxx0fx12a4xx1x12x1221a,1axxafx40是R，a4xx122aa4224a8a的取值范围为.41,0x2xx(x)1fxm0ffxx22,x0,x5m）5(2,5)．．．．Afxm()1fx=有2有3.fxm()fx=fx1fxm01yfx或fxm()()1fx=有2有3m..,0„1,exx(x)()fxkxe3f1e1,1„.x数k）1e,e．1e111e．(0,e],,．．e44ee22D(x)ykxee3f.f(x)kxe3f(x)，ykxe3eykxe11k01,1，ePxeykxegx与x0x01111又g'xg'xyxxe1P，0x2x20x0x20011,12e2ykxexkg'Aee时04e1e1e11e1ek则Dek4e2e0e2.3+1x0lnx1x1x3x(x)g(x)fx3x+1x0x21x3（）2345Df0x0(x)f(x)在x(x)f(x)g与(x)f.0fxf'(x)3x23'()0x1或x1；x3x+1f(x)x31'()0fx'()0fxfx)01x()当xf(1)1x0x0()fxyxf()且当f()x3yf(x)yg(x)5.x03logx3，，，xxxxfx）cos3x912343fxfxfxfxxxxxxxxx123412341234253，7)14，14，，．[．．333Dx03logx3fxfxfxfxa令fx,cos3x912343yaxxxxxxxx线12341234.x03logx3fxcos3x93fxfxfxfxaa3f(3)cos1x9y令x1234fxf(9)10a1有40x1x3x4.5x9xxlogxlogxxx1，，且12343132313212612xxxxxx=cos(x)由yx334123411xxg(x)xx(1,3)2x2222x2246x12xxxx14x3xxxxxxxx的31234212341234，，3.2,0-xaxf(x)(aR)1a；2a,x0x(x)f(x)①fR1；a1()(34)0fxfxx(1,0)(0,).(x)f）Ca11a.)2a2af()0x0f(x)2afx0x，，xxx)2a2af()x0f(x)2af()fx，，xxx2a2a1x0(x)()2fxx若f00aa在(),a1-?()x0()2fxax1a,1()fxRa11aa1af()f(3x4)0f()fx4)2a2a(x)00fx03x40x3x4(1,0)(0,)Cx.21,0ln(1)+,1mxxxx(x)g(x)f）x3x+1,x02,x13xf(x)g(x)程4m3(ln2,)．(ln2,4)．(ln3,2)．(ln31,1)．2D'()0fxx1x<1x3x+1'()<0，fxf(x)xf)x332在(1,0)(,1)(x)当1x0'()>0ffxyf(x)yg(x).'()0fxx1当x<1x3x+1'()<0，fxf(x)xf)x332(1,0)上单调递增，在(,1)(x)当1x0'()>0ffx在yf(x)yg(x).g(0)<1<1myf(x)yg(x)与4g(2)>1ln3m>1.ln3m.1lnx,x121xxfxfxfx111212x,x132（）．[43ln3,)．[53ln3,)．[2,5ln3]．[2,6ln2]Afxfxfx1xx与x11212x.11112111212lnxyx11y，2323fxfx故1x1x1fx212fxfx1xxx1,x11212121112x1x1lnxxxlnxx1,(x1)，231221121113xxxx03x，1x令xx343minx43xx12.gxRgx1x0是x）,02x2xfxf2xfxx,x0gx1．．．．Dgxx在fx02xx为.2，0x0gx1xQgx，为R2x,0x2xgxgx1xx0fx，,0Qyx在ln1x,x0x21xfx，y1x0在x在Rf2xfx212xx2xx20xx由2，.2.lnx1,x1且ff)()(x)f1(x2),x13）．9889e．2e2．．Bfxf)f(),.lnx1,x1f(x)1(x2),x13令11xe211x1)f()，f133535e2.e21则2lnln故ln，3xx1,e2gx10gx3令gxx，x2g1g38lngee12，gxe故2.故gx8lne18lne22.48,02xxx(x)(1,3)x(x)ff1f(x2),x02f(x)kxk(kR有4k）141．0k或8215．0kk41．0k8215．0k4A48,0x2xx(x)fxkxk()求f(x)f1求f(1,3)(x),将f(x2),x02ykx1()fx.48,0x2xxf(x)10,fxxx2()48f(x)Q当xx0,2f(x2),x021f(x)4x8xQ令0x2则2x20()(2),fxfx2211x1(x)f(x2)4x228x2222fxx2222122x4()022()fxf(x2),Q当则x1(2)fx2223+123()32fxx2xx2x,fxx248,10x2xx2ykx1ykx1f(x)2x1x2即yk2x3x3ykx1()fxykx1①当14Qf(3)1()fxykx1k10k(1,3)ykx()1fx4.4f(x)kxk即(R有4kykx1ykx1()fx在()fx在②当x,y2x3(),fx2()26fxxx3x68x当2，00y()26k又1kQykxfxx0x000yx6x8202x6214011故x，x20x:x000x+1x+100000()26fxxk8215k001f(x)kxk0k8215或k,(有4:Rkk4.第II卷（非选择题)453，0x2xxfx1．，02x14f02ff0f2则.ff0f21114f02,则:224(+1),>≤0|(−(+2≥+2．−≤|(+=|()+=数=|()+=2﹣+=−−−．2,12xaxxfxln.ax,x1xfxx1；afxa(,1)1()时fxa.xa0，a0和a0()fxa.x1f(x)x2ax.()22()0fxfx在fxxaxa()2(,1)a1.,12xxa0f(x)fx()0.0,x1alnx1()，fx0x1f(x)x2ax(xa)axfaa2.()()当a0x.，2.f22xmax1.aa21a0alnxax)0x1，f(x)()0fx().fx当aae.x2xx[1,e)f(x)0，(,)xe()0fx()，fx.()，fx，ae(x)f(e)1f(x)x2ax(xa)axfaa2.()()f.x，222.fmaxa1a1aaxa()1a0af(