Áp dụng công thức nhân đôi $\sin2x=2\sin x\cos x$
Chứng minh:
$\sin 2x = \sin \left( {x + x} \right) = \sin x\cos x + \sin x\cos x = 2\sin x\cos x$
$\sin 3x = \sin \left( {2.\dfrac{{3x}}{2}} \right) = 2\sin \dfrac{{3x}}{2}\cos \dfrac{{3x}}{2}$
`2sin((3x)/2)*cos((3x)/2)`
`=2*1/2[sin((3x)/2+(3x)/2)-sin((3x)/2-(3x)/2)]`
`= sin3x-sin0`
`=sin3x`
ĐPCM
Khái quát quá trình đấu tranh của nhân vật Tấm .Ý nghĩa của quá trình đó?
B1: Tìm n ∈ Z sao cho: a, A= (5n-7):(n+2) là nhận giá trị nguyên. b,, n∧2 +n-17 là bội của n+5 B2:Tìm xy ∈ Z biết: a,(x-3).(2y+1)=7 b,(2x+1).(3y-2)=55 c.xy-5x+y=-11
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Làm bài 3 cho mình thôi nhá ko cần làm bài 4
(3x-2y).(3x+2y) (2x-3y²)-2.(2x-3y).4+16
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tứ xay 8g thóc được 5kg gạo. hỏi xay 40kg thóc thì được bao nhiêu kg gạo
Find the mistake in the four underlined parts of each sentence and correct it. 1. The Great Wall of China is the world’s longer structure. 2. Traveling by tram is most convenient than traveling by car in this city. 3. You must taking off your shoes before entering this room. 4. Do you think there is another mountain highest than Mount Everest? 5. Ha Long Bay is the more beautiful natural wonder of Viet Nam. 6. The scenery of the Amazon rainforest in your pictures looks incredibly. 7. In my opinion, foreign tourists visit Hoi An just to its ancient houses. 8. Missouri is longer river in the USA, but it is shorter than the Amazon. 9. Meghalaya in India has more rainy or wettest weather in the world. 10. Lang Son is one of the coldest province in North Viet Nam.
Bài 1. Xác định danh từ, động từ, tính từ trong hai câu thơ sau: “Cảnh rừng Việt Bắc thật là hay Vượn hót chim kêu suốt cả ngày.”
Ex.1/ Change the following sentences from active into passive form. 1. The chief engineer was instructing all the workers of the plan. ________________________________________________________________ 2. My father is taking me to the zoo. ________________________________________________________________ 3. They are holding the meeting at Rex Hotel. ________________________________________________________________ 4. They were repairing the engine of the car. ________________________________________________________________ 5. The boys are breaking the window and taking away some pictures. ________________________________________________________________ 6. People are spending a lot of money on advertising every day. ________________________________________________________________ 7. They were using this room for the classroom. ________________________________________________________________ 8. The teacher is telling a story in the classroom . ________________________________________________________________ 9. Marry is cutting the cake with a sharp knife. ________________________________________________________________ 10. The children were looking at the women with a red hat. ________________________________________________________________
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