八年级下册数学期末考试试卷(含答? (13) - 百度文库

𡿽⣺ÿΪx 501+x1+x=72 501+x2=72

ãx=0.2x=2.2ȥ ʴΪ20%

19ͼBDΪABCDĶԽߣEBCϣAEAE=5C=2DAEBD= 13

EC=7

㡿εʣ

ֱþεʽϵֱεʵóABBEijùɶóBDij

𡿽⣺ıABCDǾΣ ABC=C=90㣬ADBC ߡC=2DAE DAE=45㣬 AB=BE AE=5

AB=BE=5 EC=7 AD=BC=12 BD=

ʴΪ13

⣺218֣226֣23-25ÿ8֣60֣ 20з̣

=13

1xx1=2x1 22x2x4=0

㡿һԪη̩ʽֽⷨһԪη̩ʽ

1ȡʽ˻Ϊ0ʽһΪ0תΪһԪһη⣻ 2ùʽ⼴ɣ

𡿽⣺1ãxx12x1=0 ֽʽãx1x2=0 ãx1=1x2=2

2a=2b=1c=4 ߡ=1+32=33 x=

21ͼʾɱ߳Ϊ1СɣABCλͼʾȷDʹABCDΪıεڽǶȣ 1ȷDλòABCDΪıΣ 2ֱд1ıεܳ

㡿ɶ

BCDΪıǾΣ1֪AABCDΪ

2ݹɶABCDijȣٸݽеܳʽʽ㼴⣮

𡿽⣺1ͼʾ

2AB=BC=ܳΪ2Ϊ2

=2+

=

2=6=10

22ͼEFΪ?ABCDĶԽBDϵ㣬AECFAEB=CFD֤AE=CF

㡿ƽıεʣ

ƽıεʵóAB=CDBAE=CDFAAS֤֤áABEաCDF̶֤ýۣ

֤ıABCDƽıΣ AB=CDABCD BAE=DCF ڡABE͡CDFУABEաCDFAAS AE=CF

23ͼABCУC=90㣬BC=5ףAB=5

ףPӵA

AC2/ٶյCƶͬʱQӵCCB1/ٶյBƶPQ˶ʱPQľ2

ף

㡿һԪη̵Ӧã

ȱʾPCCQijȻùɶгйʱtķ⼴ɣ

𡿽⣺PQ˶xʱPQľ2ڡABCУC=90㣬BC=5ףAB=5AC=

=

ף

ף

=10ף

AP=2x CQ=x CP=102xף RtCPQPC2+CQ2=PQ2 ࣨ102x2+x2=2ãx28x+12=0 ãx=2x=6

x=6ʱ CP=102x=20x=6ȥ PQ˶2ʱPQľ2

24̵꾭ijƷƷĽΪÿ80Ԫ̵Ʒÿۼ۸ڽ۵ÿۼ۲120Ԫۼ۶Ϊÿ120Ԫʱÿ۳200Ʒ۵120ԪĻϣÿ1ԪƷÿɶ۳10Ʒ۵ΪxԪÿ۳ƷΪy 1yx֮ĺϵʽдԱxȡֵΧ

2̵۸Ʒʱɱÿ컹ַ֧1000Ԫ̵ij۸Ʒ8000Ԫһ۵ΪԪ 㡿һκӦãһԪη̵Ӧã

1õۼ۶Ϊÿ120Ԫʱÿ۳200Ʒ۵120ԪĻϣÿ1ԪƷÿɶ۳10ÿ

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2

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