1. was going

2. was attending

3. was standing

4. was riding

5. were living

6. was walking

7. was going

8. was studying / was having

9. were sitting

10. was calling / wasn't / was studying

Câu 25: (NH₄)₂HPO₄ chứa N (đạm) và P (lân)

=> Chọn B

Câu 26: Chọn A

Tạo kết tủa xanh lơ là Cu(NO₃)₂ 

Cu(NO₃)₂ + 2NaOH ---> Cu(OH)₂ + 2NaNO₃

Tạo kết tủa nâu đỏ là Fe(NO₃)₃ 

Fe(NO₃)₃ + 3NaOH ---> Fe(OH)₃ + 3NaNO₃

Không hiện tượng là KNO₃

Câu 27: \(n_{CO_2}=\dfrac{3,36}{22,4}=0,15\left(mol\right)\)

PTHH: Na₂CO₃ + 2HCl ---> 2NaCl + CO₂ + H₂O

               0,15<----------------------------0,15

=> \(a=m_{Na_2CO_3}=0,15.106=15,9\left(g\right)\)

=> Chọn A

Câu 28: Chọn C (Fe bị thụ động trong H₂SO₄ đặc, nguội)

Bài 5:

Thay x=1 và y=2 vào hệ phương trình, ta được:

\(\left\{{}\begin{matrix}-m\cdot1+2=-2m\\1+m^2\cdot2=9\end{matrix}\right.\)

=>\(\left\{{}\begin{matrix}-2m=-m+2\\2m^2=8\end{matrix}\right.\Leftrightarrow\left\{{}\begin{matrix}m^2=4\\-m=2\end{matrix}\right.\)

=>m=-2

Bài 6:

a: ĐKXĐ: x>=1 và y>=-2

\(\left\{{}\begin{matrix}\sqrt{x-1}-3\sqrt{y+2}=2\\2\sqrt{x-1}+5\sqrt{y+2}=15\end{matrix}\right.\)

=>\(\left\{{}\begin{matrix}2\sqrt{x-1}-6\sqrt{y+2}=4\\2\sqrt{x-1}+5\sqrt{y+2}=15\end{matrix}\right.\)

=>\(\left\{{}\begin{matrix}-11\sqrt{y+2}=-11\\\sqrt{x-1}-3\sqrt{y+2}=2\end{matrix}\right.\)

=>\(\left\{{}\begin{matrix}\sqrt{y+2}=1\\\sqrt{x-1}=2+3=5\end{matrix}\right.\Leftrightarrow\left\{{}\begin{matrix}y+2=1\\x-1=25\end{matrix}\right.\)

=>\(\left\{{}\begin{matrix}x=26\\y=-1\end{matrix}\right.\left(nhận\right)\)

b: ĐKXĐ: x<>0 và y<>0

\(\left\{{}\begin{matrix}\dfrac{1}{x}+\dfrac{1}{y}=\dfrac{1}{12}\\\dfrac{8}{x}+\dfrac{15}{y}=1\end{matrix}\right.\)

=>\(\left\{{}\begin{matrix}\dfrac{8}{x}+\dfrac{8}{y}=\dfrac{8}{12}=\dfrac{2}{3}\\\dfrac{8}{x}+\dfrac{15}{y}=1\end{matrix}\right.\Leftrightarrow\left\{{}\begin{matrix}-\dfrac{7}{y}=\dfrac{-1}{3}\\\dfrac{1}{x}+\dfrac{1}{y}=\dfrac{1}{12}\end{matrix}\right.\)

=>\(\left\{{}\begin{matrix}y=21\\\dfrac{1}{x}=\dfrac{1}{12}-\dfrac{1}{21}=\dfrac{7-4}{84}=\dfrac{3}{84}=\dfrac{1}{28}\end{matrix}\right.\)

=>\(\left\{{}\begin{matrix}x=28\\y=21\end{matrix}\right.\left(nhận\right)\)

c: ĐKXĐ: x<>0 và y<>2

\(\left\{{}\begin{matrix}\dfrac{2}{x}+\dfrac{3}{y-2}=4\\\dfrac{4}{x}-\dfrac{1}{y-2}=1\end{matrix}\right.\)

=>\(\left\{{}\begin{matrix}\dfrac{4}{x}+\dfrac{6}{y-2}=8\\\dfrac{4}{x}-\dfrac{1}{y-2}=1\end{matrix}\right.\Leftrightarrow\left\{{}\begin{matrix}\dfrac{7}{y-2}=7\\\dfrac{2}{x}+\dfrac{3}{y-2}=4\end{matrix}\right.\)

=>\(\left\{{}\begin{matrix}y-2=1\\\dfrac{2}{x}=4-\dfrac{3}{1}=1\end{matrix}\right.\Leftrightarrow\left\{{}\begin{matrix}x=2\\y=3\end{matrix}\right.\left(nhận\right)\)

d: ĐKXĐ: x<>-2y và x<>-y/2

\(\left\{{}\begin{matrix}\dfrac{2}{x+2y}+\dfrac{1}{2x+y}=3\\\dfrac{4}{x+2y}-\dfrac{3}{2x+y}=1\end{matrix}\right.\)

=>\(\left\{{}\begin{matrix}\dfrac{6}{x+2y}+\dfrac{3}{2x+y}=9\\\dfrac{4}{x+2y}-\dfrac{3}{2x+y}=1\end{matrix}\right.\Leftrightarrow\left\{{}\begin{matrix}\dfrac{10}{x+2y}=10\\\dfrac{4}{x+2y}-\dfrac{3}{2x+y}=1\end{matrix}\right.\)

=>\(\left\{{}\begin{matrix}x+2y=1\\\dfrac{3}{2x+y}=4-1=3\end{matrix}\right.\Leftrightarrow\left\{{}\begin{matrix}x+2y=1\\2x+y=1\end{matrix}\right.\)

=>\(\left\{{}\begin{matrix}2x+4y=2\\2x+y=1\end{matrix}\right.\Leftrightarrow\left\{{}\begin{matrix}3y=1\\x+2y=1\end{matrix}\right.\)

=>\(\left\{{}\begin{matrix}y=\dfrac{1}{3}\\x=1-\dfrac{2}{3}=\dfrac{1}{3}\end{matrix}\right.\left(nhận\right)\)

e: ĐKXĐ: x>4 và y<>-2

\(\left\{{}\begin{matrix}\dfrac{3}{\sqrt{x-4}}+\dfrac{4}{y+2}=7\\\dfrac{5}{\sqrt{x-4}}-\dfrac{1}{y+2}=4\end{matrix}\right.\)

=>\(\left\{{}\begin{matrix}\dfrac{3}{\sqrt{x-4}}+\dfrac{4}{y+2}=7\\\dfrac{20}{\sqrt{x-4}}-\dfrac{4}{y+2}=16\end{matrix}\right.\Leftrightarrow\left\{{}\begin{matrix}\dfrac{23}{\sqrt{x-4}}=23\\\dfrac{5}{\sqrt{x-4}}-\dfrac{1}{y+2}=4\end{matrix}\right.\)

=>\(\left\{{}\begin{matrix}\sqrt{x-4}=1\\\dfrac{1}{y+2}=5-4=1\end{matrix}\right.\Leftrightarrow\left\{{}\begin{matrix}x-4=1\\y+2=1\end{matrix}\right.\)

=>\(\left\{{}\begin{matrix}x=5\\y=-1\end{matrix}\right.\left(nhận\right)\)

f: ĐKXĐ: x>=-1

\(\left\{{}\begin{matrix}2\left(x+y\right)+\sqrt{x+1}=4\\\left(x+y\right)-\sqrt{x+1}=-5\end{matrix}\right.\)

=>\(\left\{{}\begin{matrix}2\left(x+y\right)+\sqrt{x+1}+\left(x+y\right)-\sqrt{x+1}=4-5=-1\\\left(x+y\right)-\sqrt{x+1}=-5\end{matrix}\right.\)

=>\(\left\{{}\begin{matrix}3\left(x+y\right)=-1\\\sqrt{x+1}=-\dfrac{1}{3}+5=\dfrac{14}{3}\end{matrix}\right.\)

=>\(\left\{{}\begin{matrix}x+y=-\dfrac{1}{3}\\x+1=\dfrac{196}{9}\end{matrix}\right.\Leftrightarrow\left\{{}\begin{matrix}x=\dfrac{187}{9}\\y=-\dfrac{1}{3}-\dfrac{187}{9}=-\dfrac{190}{9}\end{matrix}\right.\left(nhận\right)\)

Nhiều quá em, em chỉ nên đăng những câu nào cảm thấy khó khăn khi giải quyết thôi

skillfully

careless(mik nghĩ zậy)

competitions

juicy

helpful

nếu kh ai giúp chắc e ngồi khók tiếng Thái quá:>

1.Minh plays volleyball very skillfully

2. We mustn’t be careful when we cross busy streets.  

3.There are many badminton competitions nowdays

4.I'd like a nice juicy orange

5.It's very helpful of you to give me a lift

khó quá

17325 nhé bạn

17325 bn nha

17325

\(a=2^{12}.5^8\)

   \(=2^8.5^8.2^4\)

   \(=\left(2.5\right)^8.16\)

    \(=10^8.16\)= 1600000000

Vậy a là số có 10 chữ số. Chúc bạn học tốt.

cảm ơn bạn.

17B

18A

19C

20C

21A

22D

23D

24B

25D

26B

27B

28A

29C

30A

a)41.36+59.89+41.84+59.11

=41.(84+36)+59.(11+89)

=41.120+59.100

=(41+59).(120+100)

=100.220=22000

b) 4.51.7+2.86.7+12.2.7

=2.2.51.7+(2.7).86+12.(2.7)

=102.(7.2)+14.86+12.14

=102.14+14.86+12.14

=14.(102+86+14)

=14.200=2800

a) 41.36 + 59.89 +41.84 +59.11= (41.56 + 41.84) + (59.89 + 59.11)= 41.(56+84) + 59.(89+11)= 41.100+ 59.100= 4100+5900=10 000

b) 4.51.7+2.86.7+12.2.7= 2.2.51.7+2.86.7+12.2.7=2.7(2.51+86+12)= 14.200=1800

c) 19.64+76.34= 19.64+19.4.34=19.(64+4.34)= 19.(64+136)= 19.200=3800

d) 35.12+65.13= 5.7.12+13.5.13= 5(7.12+13.13)=5.253=1265

e) 136.68+272.16= 136.17.4+136.2.4.4=136.4(17+2.4)= 136.4.25=136.100=13600

g) 19991999.1998-19981998.1999= 1999.10001.1998-1998.10001.1999=0

mk đg làm thì ự nhiên ấn vào hỏi đáp , mất hết những lời giải phần tiếp luôn , bn duong cx giải và đugs rồi , mk ko làm nx nhé