2 have been reading - haven't finished

3 have gone

4 am going to have

5 have washed

6 have broken

7 add - mix

8 have used

9 have lived

10 is always doing

11 am going

12 has taught

13 have already bought

14 always meet

tks 

4 đáp án là A,B,C,D nhé

1 B

2 D

3 D

4 B

5 A

6 C

7 D

8 A

9 C

1 She advised him to go on holiday when the weather got warmer

2 She warned them to keep out of that room at all time

3 He reminded me to post those letter

4 He asked them not to go into his study

5 I told him not to wait for me

7 She advised him not to go on holiday yet

8 She warned them against entering that room

1 D

2 A

3 C

4 A

5 B

6 C

7 C

8 C

9 A

10 A

Bn có chắc 100 % ko

A nhá

\(P=x^4+2x^2+1+x^4+2x^3+x^2-3\)

\(P=2x^4+2x^3+3x^2-2\)

\(P=x^2\left(2x^2+2x+3\right)-2=\dfrac{1}{2}x^2\left[\left(2x+1\right)^2+5\right]-2\ge-2\)

\(P_{min}=-2\) khi \(x=0\)

me cann't help you because i'm stupid

Sửa đề: \(D=4x^2+y^2+2xy-8x+2y+5\)

\(=x^2+2xy+y^2+2x+2y+3x^2-10x+5\)

\(=\left(x+y\right)^2+2\left(x+y\right)+1+3x^2-10x+4\)

\(=\left(x+y+1\right)^2+3\left(x^2-\frac{10}{3}x+\frac43\right)\)

\(=\left(x+y+1\right)^2+3\left(x^2-2\cdot x\cdot\frac53+\frac{25}{9}-\frac{13}{9}\right)=\left(x+y+1\right)^2+3\left(x-\frac53\right)^2-\frac{13}{3}\ge-\frac{13}{3}\forall x,y\)

Dấu '=' xảy ra khi \(\begin{cases}x+y+1=0\\ x-\frac53=0\end{cases}\Rightarrow\begin{cases}x=\frac53\\ y=-x-1=-\frac53-1=-\frac83\end{cases}\)

ko biết làm thì sao có ,thưởng ko☘

haha