Why didn't you take part in the Enghlish speaking contest last night?jenifer said -->Jenifer asked..me to take part in the English speaking contest the night before

If they weren't careless, they wouldn't make a lot of mistakes.

If they were careful, they wouldn't make a lot of mistakes

How careless of you to leave the knife on the floor.
The rain makes it impossible for us to go out.
It is dangerous to have a shower after 10pm.

1 D

2 B

3 F

4 C

5 A

6 E

17.D

18.B

19.F

20.C

21.A

22.E

Đây bạn

1 is watered by my father everymorning

2 is prepared by her mother in the kitchen

3 should be cleaned twice a day

4 repainting before Tet

5 was invited to his birthday party by John last night

6 of the car has to be repaired 

7 won't be hung in the living room

8 the most valuable painting in the national museum been stolen

9 were told this story by their grandmother when they visited her last week

10 taken by a man when we were......

11 given up smoking since last year

12 read War and Peace since 2005

C nguyên

=>2căn x+2+3 chia hết cho căn x+1

=>căn x+1 thuộc Ư(3)

=>căn x+1=1 hoặc căn x+1=3

=>x=4 hoặc x=0

\(P=\dfrac{2\sqrt{x}+5}{\sqrt{x}+1}=\dfrac{2\sqrt{x}+2+3}{\sqrt{x}+1}=2+\dfrac{3}{\sqrt{x}+1}\)`(đk:x >=0)`

Để `P in ZZ`

`=> sqrt(x) +1 in Ư(3)={+-1;+-3}`

Mà `sqrt{x} +1 >0 AA x>=0`

`=> sqrt(x) +1 in {1;3}`

`@ sqrt{x} +1 =1 => x =0`

`@ sqrt(x) +1 =3 => x=4`

b: \(\Leftrightarrow\dfrac{-m^2+3}{m}=\dfrac{13}{4}\)

\(\Leftrightarrow-4m^2+12=13m\)

\(\Leftrightarrow4m^2-13m-12=0\)

\(\Leftrightarrow\left(m-4\right)\left(4m+3\right)=0\)

\(\Leftrightarrow\left[{}\begin{matrix}m=4\\m=-\dfrac{3}{4}\end{matrix}\right.\)

a: \(E=x^4z^3y\left(\dfrac{2}{5}-0+1\right)=\dfrac{7}{5}x^4yz^3\)

b: \(E=\dfrac{7}{5}x^4yz^3=\dfrac{7}{5}\cdot2^4\cdot\dfrac{1}{2}\cdot\left(-1\right)^3=\dfrac{7}{5}\cdot8\cdot\left(-1\right)=-\dfrac{56}{5}\)

a, \(=\left(\dfrac{2}{5}+1\right)x^4z^3y=\dfrac{7}{5}x^4z^3y\)

b, Thay x = 2 ; y = 1/2 ; z = -1 vào ta được 

\(\dfrac{7}{5}.16.\dfrac{-1}{2}.1=-\dfrac{56}{5}\)