\(\frac{x}{7}=\frac{x+16}{35}\)

\(\Leftrightarrow x\cdot35=7\left(x+16\right)\)

\(\Leftrightarrow35x=7x+112\)

\(\Leftrightarrow35x-7x=112\)

\(\Leftrightarrow28x=112\)

\(\Leftrightarrow x=4\)

Vậy x = 4

\(\frac{8}{x}=\frac{7}{x-16}\)

\(\Leftrightarrow8\left(x-16\right)=x\cdot7\)

\(\Leftrightarrow8x-128=7x\)

\(\Leftrightarrow8x-7x=128\)

\(\Leftrightarrow x=128\)

Vậy x = 128

a,\(\frac{x}{7}=\frac{x+16}{35}< =>\frac{5x}{35}=\frac{x+16}{35}\)

\(< =>5x=x+16\)

\(< =>4x=16< =>x=4\)

b,\(\frac{8}{x}=\frac{7}{x-16}\)\(< =>8x-128=7x\)

\(< =>x=128\)

Tìm x

\(\frac{1}{3}+\frac{2}{2\left(x+1\right)}=1\)

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

\(\frac{1}{x+1}=1-\frac{1}{3}\)

\(\frac{1}{x+1}=\frac{3}{3}-\frac{1}{3}\)

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

\(\Rightarrow2\left(x+1\right)=3\)

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

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

Bài làm:

đkxđ: \(x\ne-1\)

Ta có: \(\frac{1}{3}+\frac{2}{2\left(x+1\right)}=1\)

\(\Leftrightarrow\frac{1}{3}+\frac{1}{x+1}=1\)

\(\Leftrightarrow\frac{x+1+3}{3\left(x+1\right)}=1\)

\(\Leftrightarrow x+4=3x+3\)

\(\Leftrightarrow2x=1\)

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

1. A = 6x^3 - 3x^2 + 2.|x| + 4 với x = -23

Thay x = -23 vào biểu thức trên, ta có:

A = 6.(-23)^3 - 3.(-23)^2 + 2.|-23| + 4

A = -74539

2. B = 2.|x| - 3.|y| với x = 12; y = -3

Thay x = 12; y = -3 vào biểu thức trên, ta có:

B = 2.|12| - 3.|-3|

B = 15

3. |2 + 3x| = |4x - 3|

ta có: 2 + 3x = \(\hept{\begin{cases}4x-3\Leftrightarrow4x-3\ge0\Leftrightarrow x\ge\frac{3}{4}\\-\left(4x-3\right)\Leftrightarrow4x-3< 0\Leftrightarrow x< \frac{3}{4}\end{cases}}\)

Nếu x >= 3/4, ta có phương trình:

2 + 3x = 4x - 3

<=> 3x - 4x = -3 - 2

<=> -x = 5

<=> x = 5 (TM)

Nếu x < 3/4, ta có phương trình:

 2 + 3x = -(4x - 3)

<=> 2 + 3x = -4x + 3

<=> 3x + 4x = 3 - 2

<=> 7x = 1

<=> x = 1/7 (TM) 

Vậy: tập nghiệm của phương trình là: S = {5; 1/7}

Ta có: -|5x - 2| \(\le\)0 \(\forall\)x

- |3y + 12| \(\le\)0 \(\forall\)y

=> 4 - |5x - 2| - |3y + 12| \(\le\)4 \(\forall\)x; y

Dấu "=" xảy ra <=> \(\hept{\begin{cases}5x-2=0\\3y+12=0\end{cases}}\)<=> \(\hept{\begin{cases}x=\frac{2}{5}\\y=-4\end{cases}}\)

Vậy MaxE = 4 khi x = 2/5 và y = -4

Ta có : E = 4 - |5x - 2| - |3y + 12| 

= 4 - (|5x - 2| + |3y + 12|)

Ta có : \(\hept{\begin{cases}\left|5x-2\right|\ge0\forall x\\\left|3y+12\right|\ge0\forall y\end{cases}}\Rightarrow\left|5x-2\right|+\left|3y+12\right|\ge0\forall x;y\)

=> \(-\left(\left|5x-2\right|+\left|3y+12\right|\right)\le0\forall x;y\)

=> \(4-\left(\left|5x-2\right|+\left|3y+12\right|\right)\le4\forall x;y\)

Dấu "=" xảy ra <=> \(\hept{\begin{cases}5x-2=0\\3y+12=0\end{cases}}\Rightarrow\hept{\begin{cases}x=\frac{2}{5}\\y=-4\end{cases}}\)

Vậy GTLN của E là 4 khi x = 2/5 ; y = - 4

1.My neighbor has vast  knowledge of past events                    (know)

2.The weatherman says there is a strong possibility of rain today          (possible)

3.Athens is famous for its ancient buildings            (fame)

4.His picture is very created (create)

5.The new isn't very cheerful (cheer)

Chúc bn hok tốt!!

k cho mk nha! Thanks bn nhìu

sai rrồi ô kê

1. warms/ gives

2. running

3. goes

4. had never worked ( word là danh từ mà -.-)

5. meet

1. The sun (warm) warms the air and (give) gives us light

2. Look at man (run) is running after the train

3.She (go) goes to school everyday 

4 Hong hiểu đề?

5. Let's (meet) meet him on the corner of this street

a)\(x\left(x+3\right)=0\)

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

vậy x=3 hoặcx=-3

b) \(\left(x-2\right)\left(5-x\right)=0\)

\(\Leftrightarrow\orbr{\begin{cases}x-2=0\\5-x=0\end{cases}}\Leftrightarrow\orbr{\begin{cases}x=2\\x=5\end{cases}}\) 

vậy x=2 hoặc x=5

c)\(\left(x-1\right)\left(x^2+1\right)=0\)

\(\Leftrightarrow\orbr{\begin{cases}x-1=0\\x^2+1=0\end{cases}}\Leftrightarrow\orbr{\begin{cases}x=1\\x^2=-1\left(ktm\right)\end{cases}}\)

vậy x=1

a) x( x + 3 ) = 0

<=> x = 0 hoặc x + 3 = 0

<=> x = 0 hoặc x = -3

b) ( x - 2 )( 5 - x ) = 0

<=> x - 2 = 0 hoặc 5 - x = 0

<=> x = 2 hoặc x = 5

c) ( x - 1 )( x² + 1 ) = 0

<=> x - 1 = 0 hoặc x² + 1 = 0

<=> x = 1 hoặc x² = -1 ( loại )

Vậy x = 1

2. A = ( 5m² - 8m² )( -n³ + 4n³ )

A = -3m².3n³

A = -9m²n³

Nhận xét : 

\(m^2\ge0\forall m\)

\(-9m^2n^3\ge0\forall m\)và n âm

\(-9m^2n^3\le0\forall m\)và n dương

Vậy với mọi m và n dương thì \(A\le0\)

3. a) -12( x - 5 ) + 7( 3 - x ) = 5

<=> -12x + 60 + 21 - 7x = 5

<=> -19x + 81 = 5

<=> -19x = -76

<=> x = 4

b) 30( x + 2 ) - 6( x - 5 ) - 24x = 100

<=> 30x + 60 - 6x + 30 - 24x = 100

<=> 0x + 90 = 100

<=> 0x = 10 ( mâu thuẫn )

Vậy x = \(\varnothing\)

=\(\frac{-13}{12}:\frac{-1}{12}-\frac{16}{15}\)\(:\frac{-2}{15}\)

=\(\frac{-13}{12}\times\left(\frac{-12}{1}\right)-\frac{16}{15}\times\frac{-15}{2}\)

=\(13-\left(-8\right)\)

=\(21\)

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I love going to sleep. Because sleeping will reduce fatigue The feeling of relief makes me want to sleep a lot. Every time I sleep, I won't be tired. The patients have to sleep a lot to improve their mental health so that they can sleep enough to have enough health to focus on their work