Nốt ạ ><
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BC
11 tháng 5 2022
vâng, áp dụng cho cả nhịp 3/8
nốt đen : 2 phách
nốt trắng : 4 phách
nốt móc đơn : 1 phách
nốt móc ghép : 0,5 phách
nốt lặng đơn : 0,5 phách
nốt lặng đen : 1 phách 
14 tháng 5 2022
nốt đen : 2 phách
nốt trắng : 4 phách
nốt móc đơn : 1 phách
nốt móc ghép : 0,5 phách
nốt lặng đơn : 0,5 phách
nốt lặng đen : 1 phách
B
26 tháng 1 2023
1 is your sister doing/is skipping
2 were
3 plays/is playing
4 do
5 saw
6 is/speaks/is coming/is staying/is visiting
7 swim
8 living
10 is
HP
26 tháng 1 2023
1. What is your sister doing now? - She is skipping.
2. There were a lot of people at the party last night.
3. Kate plays volleyball every afternoon, but she is playing badminton now.
4. We should do morning exercise.
5. He saw a big dragon in his dream.
6. Laura is from Canada. She speaks English and French. She will come back to Vietnam tomorrow. She stays in a hotel in HCM for 3 days. She visits a lot of places of interest in Viet Nam
7. My brother can swim.
8. I prefer living in a village because it is peaceful.
9. There is a chair and two tables in the room.
Sao bạn cần gấp lắm thế. Cho tớ một tick nhá
9 tháng 3 2022
CTPT: CnH2n
PTHH: CnH2n + HCl --> CnH2n+1Cl
=> \(\%Cl=\dfrac{35,5}{14n+36,5}.100\%=45,223\%\)
=> n = 3
=> CTPT: C3H6
=> B
S
21 tháng 1 2022
My mother used to work at a restaurant 3 years ago but now she doesn't
He used to be the president of Student Union but now he isn't
There used to be many trees - lined in my hometown but now there is none of them
My husband didn't use to do homework but now he does
Children didn't use to play with high-tech devices at an early age
LP
21 tháng 1 2022
1. My mom used to work at a restaurant
2. He used to be the president of Student Union
3. There used to be many tree-lined street in my hometown.
4. My husband didn't use to do the housework.
5. The children didn't use to play with high-tech devices.
NV
Nguyễn Việt Lâm
Giáo viên
17 tháng 9 2021
\(x+y=3\Rightarrow\left(x+y\right)^2=9\Rightarrow x^2+y^2+2xy=9\)
\(\Rightarrow5+2xy=9\Rightarrow xy=2\)
\(\Rightarrow\left(x-y\right)^2=x^2+y^2-2xy=5-2.2=1\)
\(\Rightarrow x-y=\pm1\)
\(A=\left(x-y\right)\left(x^2+y^2+xy\right)=\pm1.\left(5+2\right)=\pm7\)
NN
1
19 tháng 2 2022
4, were
5, was
6, were
7, was
8, were
9, was
10, were
11, were
12, was
13, was
14, was
TD
19 tháng 2 2022
4.was
5.was
6.were
7.was
8.were
9.was
10.were
11.were
12.was
13.was
14.was
9.
\(\Delta=\left(m-2\right)^2+32>0;\forall m\Rightarrow\) pt luôn có 2 nghiệm pb với mọi m
Theo hệ thức Viet: \(\left\{{}\begin{matrix}x_1+x_2=m-2\\x_1x_2=-8\end{matrix}\right.\)
\(Q=\left(x_1^2-1\right)\left(x_2^2-1\right)=\left(x_1x_2\right)^2-\left(x_1^2+x_2^2\right)+1\)
\(=\left(x_1x_2\right)^2-\left(x_1+x_2\right)^2+2x_1x_2+1\)
\(=\left(-8\right)^2-\left(m-2\right)^2+2.\left(-8\right)+1\)
\(=49-\left(m-2\right)^2\)
Do \(\left(m-2\right)^2\ge0;\forall m\)
\(\Rightarrow49-\left(m-2\right)^2\le49\)
Dấu "=" xảy ra khi \(m-2=0\Rightarrow m=2\)
10.
\(\Delta=m^2-4\left(m-2\right)=\left(m-2\right)^2+4>0;\forall m\)
\(\Rightarrow\) Pt luôn có 2 nghiệm với mọi m
Theo hệ thức VietL \(\left\{{}\begin{matrix}x_1+x_2=m\\x_1x_2=m-2\end{matrix}\right.\)
kết hợp điều kiện đề bài và hệ thức Viet ta được:
\(\left\{{}\begin{matrix}x_1+x_2=m\\x_1-x_2=2\sqrt{5}\end{matrix}\right.\)
\(\Rightarrow\left\{{}\begin{matrix}2x_1=m+2\sqrt{5}\\x_2=x_1-2\sqrt{5}\end{matrix}\right.\)
\(\Rightarrow\left\{{}\begin{matrix}x_1=\dfrac{m+2\sqrt{5}}{2}\\x_2=\dfrac{m-2\sqrt{5}}{2}\end{matrix}\right.\)
Thế vào \(x_1x_2=m-2\)
\(\Rightarrow\left(\dfrac{m+2\sqrt{5}}{2}\right)\left(\dfrac{m-2\sqrt{5}}{2}\right)=m-2\)
\(\Leftrightarrow m^2-20=4m-8\)
\(\Leftrightarrow m^2-4m-12=0\Rightarrow\left[{}\begin{matrix}m=6\\m=-2\end{matrix}\right.\)