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Bài 1:
\(\sqrt{9-4\sqrt{2}}-3\sqrt{16-6\sqrt{7}}=\sqrt{8+1-2\sqrt{8.1}}-3\sqrt{9+7-2\sqrt{9.7}}\)
\(=\sqrt{(\sqrt{8}-1)^2}-3\sqrt{(\sqrt{9}-\sqrt{7})^2}\)
\(=\sqrt{8}-1-3(\sqrt{9}-\sqrt{7})=-10+2\sqrt{2}+3\sqrt{7}\)
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1 Can she look after herself while her mother is away?
2 Could you tell me where is the station?
3 The exam was not as difficult as we thought
4 It will be impossible for them to come on Saturday
5 Their father drove to London last Monday
6 You won't need to go to the meeting next week
7 Sonia isn't interested in Roller-skating
8 You had better ride the bike more carefully next time
9 I wasn't allowed to stay out late when I was young
10 He takes care of the sick people
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6:
a: Xét tứ giác BHCD có
M là trung điểm chung của BC và HD
nên BHCD là hình bình hành
b: BHCD là hình bình hành
=>BH//CD và CH//BD
BH//CD
BH vuông góc AC
Do đó: CD vuông góc AC
=>ΔCAD vuông tại C
CH//BD
CH vuông góc AB
Do đó: BD vuông góc BA
=>ΔABD vuông tại B
c: Xét tứ giác ABDC có
\(\widehat{ABD}+\widehat{ACD}=90^0+90^0=180^0\)
=>ABDC là tứ giác nội tiếp đường tròn đường kính AD
=>ABDC nội tiếp (I)
=>IA=IB=IC=ID
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120 dm2 x 5 + 4m2 = 600 dm2 + 4 m2 = 6 m2 + 4m2 = 10 m2
89 The heavy rain prevented us from enjoying the trip
90 You had better not eat too many candied
91 He drives more slowly and more carefully than Lan does
92 The visitor spoke too quickly for me to understand