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1 She said that she was coming
2 She said that she wouldn't see me the following day
3 She said that he worked in a bank
4 She said that he was living in Paris for a few months
5 Lan said that she would be very busy the next day
6 Thu said that all the students would have a meeting the following sunday
7 Tam said that she could swim acroos that river
8 His sister said that she didn't buy that book
9 The boy said that they had to try their best to win the match
10 Her father said to her that she could go to the movies with her friends
11 Her classmate said that Lan was the most intellligent girl in their class
12 The teacher said that the sun rised in the east
\(1,4:4,9=x:\left(-28\right)\)
\(\Rightarrow\frac{1,4}{4,9}=\frac{x}{-28}\)
\(\Leftrightarrow1,4.\left(-28\right)=4,9x\)
\(\Leftrightarrow-39,2=4,9x\)
\(\Leftrightarrow x=-8\)
#H
Ta có: 1,4/4,9= x/-28
=> 1,4. (-28)= 4,9.x
=> -39,2= 4,9.x
=> x= -39,2: 4,9
=> x= -8
Although it was raining heardly, they still went to the cinema yesterday.
My brother has been playing tennis since he was ten years old
These computers have not been used for many years
We used walks at school morning but we don't anymore.
1. Although it rained hard, the still went to the cinema yesterday.
2. My brother played tennis since he was ten years old.
3. These computers haven't used for many years.
4. We used to walk to school in the morning but we don't do it any more.
a: Xét ΔHBA vuông tại H và ΔABC vuông tại A có
góc B chung
=>ΔHBA đồng dạng với ΔABC
b: S ABC=1/2*AH*BC=1/2*AB*AC
=>AH*BC=AB*AC
Do 2 đồ thị cùng tiếp xúc với \(y=2x+1\) tại \(M\left(1;3\right)\Rightarrow\left\{{}\begin{matrix}f'\left(1\right)=g'\left(1\right)=2\\f\left(1\right)=g\left(1\right)=3\end{matrix}\right.\)
Ta có:
\(h'\left(x\right)=f'\left(x\right).g\left(x\right)+f\left(x\right).g'\left(x\right)+2021\)
\(\Rightarrow\left\{{}\begin{matrix}h'\left(1\right)=f'\left(1\right).g\left(1\right)+f\left(1\right).g'\left(1\right)+2021=2.3+3.2+2021=2033\\h\left(1\right)=g\left(1\right).g\left(1\right)+2021.1=3.3+2021=2030\end{matrix}\right.\)
Phương trình tiếp tuyến:
\(y=2033\left(x-1\right)+2030\Leftrightarrow y=2033x-3\)
a: \(A=\dfrac{x^2-3+x+3}{\left(x-3\right)\left(x+3\right)}\cdot\dfrac{x+3}{x}=\dfrac{x\left(x+1\right)}{x\left(x-3\right)}=\dfrac{x+1}{x-3}\)
b: |A|=3
=>A=-3 hoặc A=3
=>x+1=3x-9 hoặc x+1=-3x+9
=>-2x=-10 hoặc 4x=8
=>x=2(nhận) hoặc x=5(nhận)
nZn = 13/65 = 0,2 (mol)
nH2SO4 = 49/98 = 0,5 (mol)
PTHH: Zn + H2SO4 -> ZnSO4 + H2
LTL: 0,2 < 0,5 => H2SO4 dư
nH2 = nH2SO4 (p/ư) = 0,2 (mol)
mH2SO4 (dư) = (0,5 - 0,2) . 98 = 29,4 (g)
VH2 = 0,2 . 22,4 = 4,48 (l)