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Những câu hỏi liên quan
DT
Đỗ Thanh Hải
CTVVIP
25 tháng 3 2021
I
1 A
2C
3 B
4 D
5 B
II
1 D
2 B
3 B
4 B
5 A
6 D
7 B
8 B
9 D
10 A
III
1 leaving => left
2 Do => would
3 visit => visiting
4 play => playing
DT
Đỗ Thanh Hải
CTVVIP
25 tháng 3 2021
3 careless
4 bleed
V
1 Hung has colllected stamps since 2000
2 The front yard isn't large enough to play soccer in
3 Milk is delivered twice a week by the milkman
4 When did you bought this computer?
5 His car doesn't run as fasst as a race car
6 Two languages can be spoken well by Lan
VI
1 T
2 F
3 T
4 T
VII
1 Mr. Nam is arriving in Hue tonight
2 They are going back to Englang in two months
3 It is not difficult to tránlate this sentence into English
4 Would you mind lending me your dictionary?
Bài này giải ở dưới r đó
P
1
17 tháng 1
Bài I:
1: Thay x=4 vào A, ta được:
\(A=\dfrac{4}{2+1}=\dfrac{4}{3}\)
2: \(B=\dfrac{3}{\sqrt{x}+1}+\dfrac{x+5}{x-1}-\dfrac{1}{\sqrt{x}-1}\)
\(=\dfrac{3}{\sqrt{x}+1}+\dfrac{\left(x+5\right)}{\left(\sqrt{x}+1\right)\left(\sqrt{x}-1\right)}-\dfrac{1}{\sqrt{x}-1}\)
\(=\dfrac{3\left(\sqrt{x}-1\right)+x+5-\sqrt{x}-1}{\left(\sqrt{x}+1\right)\left(\sqrt{x}-1\right)}\)
\(=\dfrac{3\sqrt{x}-3+x-\sqrt{x}+4}{\left(\sqrt{x}+1\right)\left(\sqrt{x}-1\right)}=\dfrac{x+2\sqrt{x}+1}{\left(\sqrt{x}+1\right)\left(\sqrt{x}-1\right)}\)
\(=\dfrac{\left(\sqrt{x}+1\right)^2}{\left(\sqrt{x}+1\right)\left(\sqrt{x}-1\right)}=\dfrac{\sqrt{x}+1}{\sqrt{x}-1}\)
3: P=A*B
\(=\dfrac{\sqrt{x}+1}{\sqrt{x}-1}\cdot\dfrac{x}{\sqrt{x}+1}=\dfrac{x}{\sqrt{x}-1}\)
P<=4
=>P-4<=0
=>\(\dfrac{x-4\sqrt{x}+4}{\sqrt{x}-1}< =0\)
=>\(\dfrac{\left(\sqrt{x}-2\right)^2}{\sqrt{x}-1}< =0\)
=>\(\sqrt{x}-1< 0\)
=>\(\sqrt{x}< 1\)
=>0<=x<1
Kết hợp ĐKXĐ, ta được: 0<=x<1
DT
Đỗ Thanh Hải
CTVVIP
25 tháng 3 2021
3 careless
4 bleed
V
1 Hung has colllected stamps since 2000
2 The front yard isn't large enough to play soccer in
3 Milk is delivered twice a week by the milkman
4 When did you bought this computer?
5 His car doesn't run as fasst as a race car
6 Two languages can be spoken well by Lan
VI
1 T
2 F
3 T
4 T
VII
1 Mr. Nam is arriving in Hue tonight
2 They are going back to Englang in two months
3 It is not difficult to tránlate this sentence into English
4 Would you mind lending me your dictionary?
31 tháng 10 2021
3 careless
4 bleed
V
1 Hung has colllected stamps since 2000
2 The front yard isn't large enough to play soccer in
3 Milk is delivered twice a week by the milkman
4 When did you bought this computer?
5 His car doesn't run as fasst as a race car
6 Two languages can be spoken well by Lan
VI
1 T
2 F
3 T
4 T
VII
1 Mr. Nam is arriving in Hue tonight
2 They are going back to Englang in two months
3 It is not difficult to tránlate this sentence into English
4 Would you mind lending me your dictionary?
NM
0
HN
0
11 tháng 8 2021
a: Áp dụng định lí Pytago vào ΔADC vuông tại D, ta được:
\(AC^2=AD^2+DC^2\)
\(\Leftrightarrow AC^2=8^2+15^2=289\)
hay AC=17cm
b: Áp dụng hệ thức lượng trong tam giác vuông vào ΔADC vuông tại D có DM là đường cao ứng với cạnh huyền AC, ta được:
\(DM\cdot AC=AD\cdot DC\)
\(\Leftrightarrow DM=\dfrac{120}{17}\left(cm\right)\)
10 tháng 9 2021
a ) Theo định lý py-ta-go trong ΔADC, ta có :
AC^2 = AD^2 + CD^2
= 8^2 + 15^2
= 64 + 225
= 289
=> AC = 17 (cm)
b ) Ta có :
Xét tam giác ΔMDA và ΔDCA, có :
góc A chung
góc AMD = góc ADC = 90 độ
=> ΔMDA ∼ ΔDCA (G.G)
=> MD/CD = AD/AC
=> MD = CD.AD/AC
= 15.8/17
= 7,1 (cm)
HA
0
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