八年級數(shù)學(xué)上冊期末試卷含答案

DDDDD DDDDDD D#ODD8D21.：(1) =aa—a+3a—3+以—2a=2aa—3.(2) =mn(m2-9)=mn(m+3)(m-3).：(1) (x+3)(x-3), 12-2(x+3)=x-3, x=3. ：x=3 ,(x+3)D(x—3尸0,x=3TOC\o"1-5"\h\z(2) DDDDDDDDDD +DDDDDDDDDD =DDDDDDDDDD +DDDDDDDDDD ,DDDDDDDDDD +DDDDDDDDDD =DDDDDDDDDD +DDDDDDDDDD , ,DDDDDDDDDD -DDDDDDDDDD =DDDDDDDDDD -DDDDDDDDDD , ODDDDDDDDD=DDDDDDDDDD, , , ,(x-8)(x-6)=(x-4)(x-2). , 8x=40, x=5. x=5 ,(X-2)D(x-8)(x-4)(x-6)=9D0,x=5 . x=5.：(1)=DDDDDDDDDD =DDDDDDDDDD =c.a=l,b=2,c=3, =3.(2)=DDDDDDDDDD DDDDDDDDDDD +1=DDDDDDDDDD +1. a口O,aDD2,a1.a=l, =1+1=2.：DBPODPDC,DBPCHC+DD,DPOADOEF,DPOA^E+DF.DA+DB+DBPO卻POA^36OD,DA加B+DC+DD+DE+DF=360D.：CEBFABDCD,DA=DD.CEdBF. CEBFCE=BF, CEDBF. ：DABFDDCE,AB=CE)DA=DD,AF=DE>：CEBFABDCD,DA=DD.CEdBF. CEBFCE=BF, CEDBF. ：DABFDDCE,AB=CE)DA=DD,AF=DE>CE=BF, CEOBF.DAB用DDCE.CE=BF,DAFBTDEC.26(1)：AD,BM,CNDABCDABO^DDDDDDDDDDABC,DBCO^DDDDDDDDDDACB,DCAO^DDDDDDDDDDCAB.DDABC九ACB九CAB=180D,DABO九BCO九CAO=DDDDDDDDDD (DABC卻ACB九CAB)=DDDDDDDDDD D180D=90D.：DBOD=0BAO北ABQDBAO=0CAQDBOD=0CAO而ABO=0DDDDDDDDD(0BAC+0ABQ=DDDDDDDDDD(180D—口ACB)=90D-DDDDDDDDDDDDDDDDD(180D—口ACB)=90D-DDDDDDDDDDDACB=90D-DBCO.OEOBC,D0EC=90D,DC0E=90D-DECO.DBODjCOE.27.AEF,EF=A^DF,3,0AEDABD,DBE=DE.DAEBDFED27.33DDAEBODFED.DAB=FD,DB=DFDE.DADDABC,BC.DBD=CD=DDDDDDDDDD BC.BC.DBC=2AB,DAB=DDDDDDDDDDDAB=BD=CD.DDBADTBDA,FD=CD.DDADCTB+DBAD,DADFTADB九FDE,DDADCTADF.DADCDADF,AD=AD,vZADC=ZADF,DC=DF,DDADCDDADF.DAC=AF.DAF=AE+FE=2AE,DAC=2AE.28.：(1)xm/min,3xm/min.,ODDDDDDDDD=DDDDDDDDDD+20,x=70. x=7070m/min.2100⑵,DDDDDDDDDD+r7c oDDDDDDDDDD70x3+1=41<42,：(1)DBDDm,CEDm,TOC\o"1-5"\h\zD D BDAT CEA=90D .D D BAC=90D,D D BAD九 CAE=90D .D D BAD九 ABD=90D ,D D CAEJ ABD.DAB=AC,DDADBODCEA.DAE=BD,AD=CE.DDE=AE+AD=BD+CE.⑵口DBDAtBAC=cr,DDDBA卻BADJBAD旬CAE=180D-a.DDDBATCAE.DDBDATAEC=cr,AB=AC,DDADBODCEA.DAE=BD,AD=CE.DDE=AE+AD=BD+CE.(2),DADBODCEA,BD=A^DDBAACAE,D D ABF DACF ,D D ABFT CAFTO口 .D D DBA卻 ABFJ CAE卻CAF.D D DBFT FAE.DBF=AF,DDDB用DEAF.DDF