\(21_{10}=10101_2\)

\(\dfrac{24}{5}\)

\(\dfrac{24}{5}\)

24/5

Đề đâu bạn :v ?

à thấy ròi :D

-Chúng có cơ quan giác bám tăng cường
-dinh dưỡng bằng cách thẩm thẫu chất dinh dưỡng có sẵn có ruột người qua cơ thể nên rất hiệu quả

-Mỗi đốt có 1 cơ quanh sinh sản lưỡng tính 
Thi tốt bn nhé
 

a)\(=>x=\left(-\dfrac{1}{2}+\dfrac{1}{4}\right):2=-\dfrac{1}{8}\)

bây h mới thấy phần b

\(=>\dfrac{1}{3}\left(x+1\right)=\dfrac{13}{3}-\dfrac{4}{3}=\dfrac{9}{3}=3\)

\(=>x+1=3:\dfrac{1}{3}=9\)

\(=>x=9-1=8\)

a) \(2x-\dfrac{1}{4}=\dfrac{-1}{2}\)

    \(2x=\dfrac{-1}{2}+\dfrac{1}{4}\)

   \(2x=-\dfrac{1}{4}\)

    \(x=-\dfrac{1}{4}\div2\)

    \(x=-\dfrac{1}{8}\)

b) \(\dfrac{13}{3}-\dfrac{1}{3}\cdot\left(x+1\right)=\dfrac{4}{3}\)

              \(\dfrac{1}{3}\cdot\left(x+1\right)=\dfrac{13}{3}-\dfrac{4}{3}\)         

              \(\dfrac{1}{3}\cdot\left(x+1\right)=3\)

                     \(x+1=3\div\dfrac{1}{3}\)

                    \(x+1=9\)

                   \(x=9-1\)

                   \(x=8\)

Ư(-21)={-21, -7, -3, -1, 1, 3, 7, 21}  

-21 , -7 , -3 , -1 , 1 , 3 , 7 , 21

\(Ư\left(-21\right)=\pm1;\pm3;\pm7;\pm21.\)

Bạn sai cta nhé, sắp not xắp

Tham khảo

1. A special kind of tea is sold here 

2. All the cars and trucks have been searched 

3. He was put in prison by the goverment last years

4. We will be met by her parents at the station tomorrow 

5. A meeting is being held by Mr. Brown in the hall 

Bài 2 

1 Tea can't be made with cold water

2 Some of my books have been taken away.

3 Some pictures were taken away by the boys.

4 This room may be used for the classroom.

5 This machine mustn't be used after 5:30 p.m 

6 Mr Cole used to be visited at weekends by John.

7 All the homework ought to be done by her

1.C

2.D

3.A

4.B

5.A

1 C

2 D

3 D

4 A

5 D

1. C

2. D

3. A

4. D

5. A

7:

a: ĐKXĐ: x>=0; x<>1

\(D=\dfrac{1}{2\sqrt{x}-2}-\dfrac{1}{2\sqrt{x}+2}+\dfrac{\sqrt{x}}{1-x}\)

\(=\dfrac{1}{2\left(\sqrt{x}-1\right)}-\dfrac{1}{2\left(\sqrt{x}+1\right)}-\dfrac{\sqrt{x}}{\left(\sqrt{x}+1\right)\left(\sqrt{x}-1\right)}\)

\(=\dfrac{\sqrt{x}+1-\sqrt{x}+1-2\sqrt{x}}{2\left(\sqrt{x}-1\right)\left(\sqrt{x}+1\right)}\)

\(=\dfrac{-2\left(\sqrt{x}-1\right)}{2\left(\sqrt{x}-1\right)\left(\sqrt{x}+1\right)}=\dfrac{-1}{\sqrt{x}+1}\)

b: Khi x=4/9 thì \(D=\dfrac{-1}{\dfrac{2}{3}+1}=-1:\dfrac{5}{3}=-\dfrac{3}{5}\)

c: |D|=1/3

=>D=-1/3 hoặc D=1/3

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

=>\(\sqrt{x}+1=3\)

=>\(\sqrt{x}=2\)

=>x=4

6:

a: \(C=\left(\dfrac{\sqrt{x}}{3+\sqrt{x}}+\dfrac{x+9}{9-x}\right):\left(\dfrac{3\sqrt{x}+1}{x-3\sqrt{x}}-\dfrac{1}{\sqrt{x}}\right)\)

\(=\dfrac{\sqrt{x}\left(3-\sqrt{x}\right)+x+9}{\left(3-\sqrt{x}\right)\left(3+\sqrt{x}\right)}:\dfrac{3\sqrt{x}+1-\sqrt{x}+3}{\sqrt{x}\left(\sqrt{x}-3\right)}\)

\(=\dfrac{3\sqrt{x}-x+x+9}{\left(3-\sqrt{x}\right)\left(3+\sqrt{x}\right)}\cdot\dfrac{-\sqrt{x}\left(3-\sqrt{x}\right)}{2\sqrt{x}+4}\)

\(=\dfrac{3\left(\sqrt{x}+3\right)}{3+\sqrt{x}}\cdot\dfrac{-\sqrt{x}}{2\sqrt{x}+4}=\dfrac{-3\sqrt{x}}{2\sqrt{x}+4}\)

b: C<-1

=>C+1<0

=>\(\dfrac{-3\sqrt{x}+2\sqrt{x}+4}{2\sqrt{x}+4}< 0\)

=>\(-\sqrt{x}+4< 0\)

=>\(-\sqrt{x}< -4\)

=>\(\sqrt{x}>4\)

=>x>16

\(C=\left(\dfrac{\sqrt{x}}{3+\sqrt{x}}+\dfrac{x+9}{9-x}\right):\left(\dfrac{3\sqrt{x}+1}{x-3\sqrt{x}}-\dfrac{1}{\sqrt{x}}\right)\\ =\left(\dfrac{\sqrt{x}}{3+\sqrt{x}}+\dfrac{x+9}{\left(3-\sqrt{x}\right)\left(3+\sqrt{x}\right)}\right):\left(\dfrac{3\sqrt{x}+1}{\sqrt{x}\left(\sqrt{x}-3\right)}-\dfrac{1}{\sqrt{x}}\right)\\ =\left(\dfrac{\sqrt{x}\left(3-\sqrt{x}\right)}{\left(3+\sqrt{x}\right)\left(3-\sqrt{x}\right)}+\dfrac{x+9}{\left(3-\sqrt{x}\right)\left(3+\sqrt{x}\right)}\right):\left(\dfrac{3\sqrt{x}+1}{\sqrt{x}\left(\sqrt{x}-3\right)}-\dfrac{\sqrt{x}-3}{\sqrt{x}\left(\sqrt{x}-3\right)}\right)\\ =\dfrac{3\sqrt{x}-x+x+9}{\left(3+\sqrt{x}\right)\left(3-\sqrt{x}\right)}:\dfrac{3\sqrt{x}+1-\sqrt{x}+3}{\sqrt{x}\left(\sqrt{x}-3\right)}\)

\(=\dfrac{3\sqrt{x}+9}{\left(3+\sqrt{x}\right)\left(3-\sqrt{x}\right)}\cdot\dfrac{-\sqrt{x}\left(3-\sqrt{x}\right)}{2\sqrt{x}+4}\\ =\dfrac{3\left(\sqrt{x}+3\right)}{\left(3+\sqrt{x}\right)\left(3-\sqrt{x}\right)}\cdot\dfrac{-\sqrt{x}\left(3-\sqrt{x}\right)}{2\sqrt{x}+4}\\ =\dfrac{-3\sqrt{x}}{2\sqrt{x}+4}\)

Để `C < -1` Ta có :

 \(\dfrac{-3}{2\sqrt{x}+4}< -1\\ \Leftrightarrow\dfrac{-3}{2\sqrt{x}+4}+1< 0\\ \Leftrightarrow\dfrac{-3}{2\sqrt{x}+4}+\dfrac{2\sqrt{x}+4}{2\sqrt{x}+4}< 0\\ \Leftrightarrow-3+2\sqrt{x}+4< 0\\ \Leftrightarrow2\sqrt{x}+1< 0\\ \Leftrightarrow2\sqrt{x}< -1\\ \Leftrightarrow\sqrt{x}< -\dfrac{1}{2}\\ \Leftrightarrow x< \dfrac{1}{4}\)

bài hình mà không gửi hình, làm bài = niềm tin hả bạn