ai làm đk mình k cho

Ta có:  a < b     =>    2a < a + b

           c < d      =>    2c < c + d

           m < n     =>    2m < m +n

suy ra:    2 ( a + c + m)  < a + b + c + d + m + n

=>   \(\frac{a+c+m}{a+b+c+d+m+n}< \frac{1}{2}\)

câu 1 mk ko biết 

2) => If you are a vegetariane, you won"t eat meat.

         If you are a teacher, you will work hard.

One of my hobbies is listening to music, especially English songs. My hobby started when I was a first – year student at Da Nang University of Technology. I spend much time on it. I can listening when I am doing my housework such as clean the floor, wash clothes, wash dish…or when I sleep…I love Taylor Swift, Rihana…they are great singers. I can learn English vocabulary when listening to English songs and it also make me feel relaxed.

I think it a good hobby and I will never stop it.

Watching television is my favourite activities I use to do in my free time. I love watching sports programs on Saturday mornings and cartoons on Sunday afternoons. I usually watch movie during all days of week after I have completed my homework at school. At night, I especially enjoy watching situation comedies and movies. If I have a huge number of  school work, I try to manage my schedule so that I will able to see at least 1 of my favorite TV shows. Watching TV isn’t the only indoor activity that I can do in my free time. I also have some other favorite activities  such as going shopping with my mother or friends and making paper flowers. However, when I have free time, I spend a lot of time on watching TV than other activities. Watching TV can support me not only relax but also build my knowledge about the open world.

K nhé?

1)  ( 5 - 3x ) ( 1 + x ) = 0

=> \(\orbr{\begin{cases}5-3x=0\\1+x=0\end{cases}}\)

=> \(\orbr{\begin{cases}x=\frac{5}{3}\\x=-1\end{cases}}\)

Vậy x = - 1 hoặc x = \(\frac{5}{3}\)

2) x² - 3x = 0

=> x ( x - 3 ) = 0

=> \(\orbr{\begin{cases}x=0\\x-3=0\end{cases}}\) 

=> \(\orbr{\begin{cases}x=0\\x=3\end{cases}}\)

Vậy x = 0 hoặc x = 3

3) 4x + 2x² = 0

=> 2x ( x + 2 ) = 0

=> \(\orbr{\begin{cases}2x=0\\x+2=0\end{cases}}\)

=> \(\orbr{\begin{cases}x=0\\x=-2\end{cases}}\)

Vậy x = 0 hoặc x = - 2

\(a,\left(5-3x\right)\left(1+x\right)=0\)

\(\Leftrightarrow\orbr{\begin{cases}5-3x=0\\1+x=0\end{cases}\Leftrightarrow\orbr{\begin{cases}3x=5\\x=-1\end{cases}\Leftrightarrow}\orbr{\begin{cases}x=\frac{5}{3}\\x=-1\end{cases}}}\)

vậy_

\(b,x^2-3x=0\)

\(\Leftrightarrow x\left(x-3\right)=0\)

\(\Leftrightarrow\orbr{\begin{cases}x=0\\x-3=0\end{cases}\Leftrightarrow\orbr{\begin{cases}x=0\\x=3\end{cases}}}\)

vậy_

\(c,4x+2x^2=0\)

\(\Leftrightarrow x\left(4+2x\right)=0\)

\(\Leftrightarrow\orbr{\begin{cases}x=0\\4+2x=0\end{cases}\Leftrightarrow\orbr{\begin{cases}x=0\\2x=-4\end{cases}\Leftrightarrow}\orbr{\begin{cases}x=0\\x=-2\end{cases}}}\)

vậy_

a, Số hs giỏi là:

40 . 1/8 = 5 (hs)

    Số hs còn lại là:

40 - 5 = 35 (hs)

    Số hs khá là:

35 . 2/5 = 14 (hs)

    Số hs yếu là:

14 . 3/7 = 6 (hs)

    Đ/S: giỏi: 5 hs

            khá: 14 hs

            trung bình: 6 hs 

A) x-1=0                    x+2=0

x=1                         x=-2 

           vậy x =1 hoặc x=-2 

B) 2x-1=0                   3x+2=0

2x=1                     3x=2

x=\(\frac{1}{2}\)             x=\(\frac{2}{3}\)

vậy x=1/2 hoặc x=2/3 

c) 2x=0                   x-1/2 =0

x=0                      x=1/2

               vậy x=0 hoặc x=1/2

a) ( x - 1 ) ( x + 2 ) = 0

=> \(\orbr{\begin{cases}x-1=0\\x+2=0\end{cases}}\)

=> \(\orbr{\begin{cases}x=1\\x=-2\end{cases}}\)

Vậy x = 1 hoặc x = - 2

b) ( 2x - 1 ) ( 3x + 2 ) = 0

=> \(\orbr{\begin{cases}2x-1=0\\3x+2=0\end{cases}}\)

=> \(\orbr{\begin{cases}2x=1\\3x=-2\end{cases}}\)

=> \(\orbr{\begin{cases}x=\frac{1}{2}\\x=\frac{-2}{3}\end{cases}}\)

Vậy x = \(\frac{1}{2}\)hoặc x = \(\frac{-2}{3}\)

c)  \(2x\left(x-\frac{1}{2}\right)=0\)

=> \(\orbr{\begin{cases}2x=0\\x-\frac{1}{2}=0\end{cases}}\)

=> \(\orbr{\begin{cases}x=0\\x=\frac{1}{2}\end{cases}}\)

Vậy x = 0 hoặc x = \(\frac{1}{2}\)

Vì \(\left|x+4\right|\ge0;\left|y-3\right|\ge0\)

   mà |x+4| + |y-3| =3 và |x+4| ; |y-3| thuộc Z

\(\Rightarrow\left(\left|x+4\right|;\left|y-3\right|\right)\in\left\{\left(0;3\right)\left(1;2\right)\left(3;0\right)\left(2;1\right)\right\}\)

Tương ứng \(\left(x;y\right)\in\left\{\left(-4;6\right);\left(-3;5\right);\left(-1;3\right);\left(-2;4\right)\right\}\)

Vậy \(\left(x;y\right)\in\left\{\left(-4;6\right);\left(-3;5\right);\left(-1;3\right);\left(-2;4\right)\right\}\)

\(\frac{-1}{5}\)

-1/5 . (9/8 + 16/32 - 12/46) - 9/17

= -1/5 . (9/8 + 1/2 - 6/23) - 9/17

= -1/5 . (9/8 + 4/8 - 6/23) - 9/17

= -1/5 . (13/8 - 6/23) - 9/17

= -1/5 . 251/184 - 9/17

= -251/920 - 9/17

= -4267/15640 - 8280/15640

= -12547/15640