chọn và giải thích ạ
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37 C
38 B
39 D
40 A
37 C
38 C
39 A
40 D
36 C
37 A
38 B
39 D
40 B
36 A
37 A
38 A
39 B
40 D
\(AB=2.\dfrac{6.\sqrt{10^2-6^2}}{10}=9,6\left(cm\right)\)
\(\left(3+8\right).4=44\)
\(\left(9+7\right).2=32\)
\(\left(8+7\right).?=75\Rightarrow?=\dfrac{75}{15}=...\)
1 This meal didn't cost as much as I though
2 I've never seen such a bad film
3 Is that the best you can do?
4 There is less dry in the North than there is in the south of England
5 She was not expected to be so beautiful
6 The meeting went more smoothly than it did last time
7 You lead
8 Helen earns twice as much as I do
9 The other teams have gone less games than they
4.
\(=\dfrac{4\left(\sqrt{7}-\sqrt{3}\right)}{\left(\sqrt{7}+\sqrt{3}\right)\left(\sqrt{7}-\sqrt{3}\right)}+\dfrac{2\left(\sqrt{7}+3\right)}{\left(\sqrt{7}-3\right)\left(\sqrt{7}+3\right)}\)
\(=\dfrac{4\left(\sqrt{7}-\sqrt{3}\right)}{4}+\dfrac{2\left(\sqrt{7}+3\right)}{-2}=\sqrt{7}-\sqrt{3}-\sqrt{7}-3\)
\(=-\sqrt{3}-3\)
5.
Hàm đồng biến khi \(2m>0\Leftrightarrow m>0\)
15: Pha dao động là pi+pi/2=3/2pi
=>Chọn C
14:
Khi t=1,25 thì \(x=2\cdot cos\left(2.5pi-\dfrac{pi}{6}\right)=1\)
=>Chọn A
15: Pha dao động là pi+pi/2=3/2pi
=>Chọn C
14:
Khi t=1,25 thì \(x=2\cdot cos\left(2.5pi-\dfrac{pi}{6}\right)=1\)
=>Chọn A
16: \(10t-\dfrac{3}{2}pi=\dfrac{2}{3}pi\)
=>10t=2/3pi+3/2pi=13/6pi
=>t=13/60pi
\(x=6\cdot cos\left(10\cdot\dfrac{13}{6}pi-\dfrac{3}{2}pi\right)\)
\(=6\cdot cos\left(\dfrac{2pi}{3}\right)=-3\)
=>Chọn C
\(cos\alpha=\dfrac{1,69}{4}\Rightarrow\alpha\approx65^0\)