参考答案
一、选择题： 1.B 2.D 6.B 7.B 二、填空题： 11. 3.84?106 15. ?14x?2y
3.A 8.C 4.A 9.D 5.D 10.B
925
12.120? 16.324
13. 14.20cm
三、解答题： 17．略
18．解：原式?2?1?2?(?8? =3?2 =1
14)
（6分）
19．?AB//CD(已知)
??B??C(两直线平行，内错角相等)
又??C??D?180?(两直线平行，同旁内角互补)
??B??D?180(等量代换)
?又??B?60?(已知)
??D?120
2? (每空0.5分)
20．解：(a?b)?17
a?2ab?b?17
22将ab?3代入得
a?b?17?6 a?b?11
222222
2 (3分)
(a?b)?a?2ab?b
将a?b?11,ab?3代入得
(a?b)?11?6=5
236222
24 (6分)
21．(1)解：原式?5xy?(?y)?(4xy)
??20xy69?(4xy )24
??5x4y5 (5分)
(2)解：原式=4x2?12x?9?(9x2?4) =4x2?12x?9?9x2?4
=?5x2?12x?13
(10分)
22．(1)解：a?1?15%?30%?10%?5%?15%?25%
360?25%?90?
2010%?200人
(2) 200?25%?50人
补统计图略
23．解：[x2?4xy?y2?(2x2?xy?4xy?2y)2?6y2]?(?x) =[x2?4xy?y2?2x2?3xy?2y2?6y2]?(?x) =?(?x2?7xy)?(?x) =x?7y
将x?5,y??1代入原式得 =5+7
=12
24．解：?CE平分?ACD,?ACD?190?
??ACE??ECD?1?2?ACD?50??FG//GE??GFC??ACE?50???AGF?20? ??GAF?180?20?50?110?
??BAC?70?又??ACD?100???ACB?80???B?180?70??80?
=30?
(2分)
(4分) (6分) (8分) (10分)
(6分)
(10分)
25．(1) b?a
(2分) (4分) (6分) (8分) (10分)
(2)①b2?2ab?a2 ②c2?2ab
(3) b2?a2?c2 (4)10
26．(1) ?OE平分?COF
??COE??EOF???FOB??AOB???EOF??FOB?121212?COF?AOF?COF?12?AOF?12?COA
即?EOB?12?COA
又?CB//OA??COA??C?180??COA?80??EOB?12???COA?40? (2) ?CB//OA
?COB??BOA??BOA??FOB
??CBO??FOB?12(?FOB??FBO)
又??CFO??FOB??FBO??CFO?2?CBO即?OBC??OFC?1:2 (3) ?BC//AO
??C??COA?180?
??C?100??COA?80??A?100??
??COA??A?180? ?CO//AB??ABO??COB
??ABO??OEC??OEC??COB
又??OEC??EOB??CBO??COB??EOB??CBO??COE??EOB??CBO??COE??CBO??COE??CBO??FOB
??COE??FOB??COE??FOE,?FOB??BOA??COE??FOE??FOB??BOA即?EOF??FOB??FOB?14?COA?
??DEC??OBA?3?FBO?60