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(4)(7,42)1.AB6,1,1,2,2,3,4.6().(A)13(B)14(C)15(D)162.abc,x=b2+1a,y=c2+1b,z=a2+1c.xyz().(A)2(B)2(C)2(D)23.ABCD,B=D=90,AD=DC.SABCD=12,AB+BC=().(A)6(B)43(C)52(D)364.f(x)=ax2+bx+c11.p=|a-b+c|+|2a+b|,q=|a+b+c|+|2a-b|.().(A)pq(B)p=q(C)pq(D)pq5.x1x2x3x4x5,(2005-x1)(2005-x2)(2005-x3)(2005-x4)(2005-x5)=242,x21+x22+x23+x24+x25().(A)1(B)3(C)5(D)76.2,ABCD,DCAB,2ACBDMNAB,MNADBC.ABDCMN().(A)AB+DC=5MN(B)ABDC=MN2(C)ABMN-1=MNDC-1(D)1AB+1DC=2MN(7,28)1.3n.1335657111179182218932.xm2x2+(2m+3)x+1=01;xx2+(2a+m)x+2a+1-m2=004.a.3.,10.678923141120.95.411018,10.44.4,OABC,BC=a,CA=b,A-B=90.O.(20):c,xyz,1+|x+y+z|+|xy+yz+zx|+|xyz|c(|x|+|y|+|z|).5(25)5,ABCABOBCCAEF.EFOP.:CPAB.(25)f(x)=ax2+bx+cA(x1,y1)B(x2,y2),a2+(y1+y2)a+y1y2=0.(1):y1=-ay2=-a;(2):f(x)x;(3)xf(x)0{x|xmxn}(nm0),xcx2-bx+a0.1.C.66,,.,,10;,(3,2,2)1;(3,2,1)22=4,,1+4=5.,10+5=15.2.B.xyz=b2+1ac2+1ba2+1c=b2+1bc2+1ca2+1a=a+1ab+1bc+1c.abc,,a+1a2,b+1b2,c+1c2,.,xyz8.xyz2.3.B.77,DABDCK.AD=DC,,AC.B=D=90,,A+C=180.BCK.,DBK,SDBK=SABCD=12.,DB=DK=26.AB+BC=BK=2DB=43.4.C.1,f(0)=c=0,f(1)=a+b+c0,a+b0,f(-1)=a-b+c=a-b0.a0x=-b2a1,2a+b0.2a-b=a+(a-b)0,,p=-(a-b)+(2a+b)=a+2b,q=(a+b)-(2a-b)=-a+2b.p-q=(a+2b)-(-a+2b)=2a0,pq.5.A.x1x2x3x4x5,5120071,5.2425,242=2(-2)46(-6),,5(2005-xi)(i=1,2,3,4,5)2,-2,4,6,-6.(2005-x1)2+(2005-x2)2+(2005-x3)2+(2005-x4)2+(2005-x5)2=22+(-2)2+42+62+(-6)2=96.,520052-4010(x1+x2+x3+x4+x5)+(x21+x22+x23+x24+x25)=96,x21+x22+x23+x24+x25=96-520052+4010(x1+x2+x3+x4+x5)1(mod10).6.D.ACBDO.MOAB=DODB=COCA=ONAB.,MO=ON,MN=2MO.MODC+MOAB=AMAD+DMAD=1,1AB+1DC=1MO=22MO=2MN.1.n2-2n+3.n3+3+5+7++(2n-3)=2+(1+3+5+7++2n-3)=2+(1+2n-3)(n-1)2=n2-2n+3.2.-1.m2=1,m=1,=(2m+3)2-4m2=12m+90.m=1.f(x)=x2+(2a+1)x+2a,f(0)f(4)=2a(20+10a)0,a(a+2)0.,-2a0.a=-1.3.29.5x,,95x+23+14+11+209=5x+689.5x+689x.x17.5517-1=84.10y,101810+1=181.,y+84+68181,y29.1029.4.12a2+b2.OCD,DB.A=B+90=B+CBD=ABD,,CDB=ACD.,AC=BD,BD=AC=b.,CD=a2+b2.,O12a2+b2.M,,xyz,M2(x+y+z)2+2|xy+yz+zx|=x2+y2+z2+2(xy+yz+zx+|xy+yz+zx|)x2+y2+z2.x2+y22|xy|,y2+z22|yz|,x2+z22|xz|,2(x2+y2+z2)2(|xy|+|yz|+|zx|).x2+y2+z2,3(x2+y2+z2)(|x|+|y|+|z|)2,x2+y2+z213(|x|+|y|+|z|)2.M213(|x|+|y|+|z|)2.,c=33.88,AEBFQ,,QABC,CQAB.FPK,PK=PF,EFKE.PEF=PFE=EAF.PQABH.EQF=180-AQF61=180-(90-EAF)=90+EAF=90+PEF,K=12EPF=12(180-2PEF)=90-PEF,,EQF+K=180.KFQE.PK=PE=PF,P.,PQ=PF.,PQF=PFQ=PFB=FAB=FAH.AHQF.,PHA=QHA=180-QFA=90,,PHAB,PQAB.CPQ.CPAB.(1)a2+(y1+y2)a+y1y2=0,(a+y1)(a+y2)=0.y1=-ay2=-a.(2)a0,f(x),AB-a0,,x;a0,f(x),AB-a0,,x.f(x)x.(3)ax2+bx+c0{x|xmxn}(nm0),,a0,b0,c0.,cx2+bx+a=0x1=1m,x2=1n.,cx2-bx+a=0x1=-1m,x2=-1n.nm0,,-1n-1m.cx2-bx+a0x-1mx-1n.(,246004,246142)(5)(7,42)1.x2-3x+1=0x4-px2+q=0,(p+q)2008().(A)2(B)4(C)6(D)82.y=1x2+ax+b(,ab)().(A)a2-4b0(B)a2-4b0(C)a2-4b0(D)ab,3.ABCr,BC=a,AC=b,AB=c,hahbhc,ha+hb+hc=9r.ABC().(A)(B)(C)(D)4.xyz,x(y-z)=y(z-x)q=z(y-x)q2,q().7120071