There are six rooms in my house – one living room, two bedrooms, two bathrooms and one kitchen. Among the rooms, my bedroom is the smallest but also the prettiest one. My parents allow me to decorate it on my own, so I put everything that I love into it. The walls have a sweet pink color, and I hang a lot of pictures of me, my family and my friends in a corner. The bed is not very big, and the bed sheets as well as pillows all have light pink color. There is a thick rug in my room, and I usually sit right on the floor to read books or playing video game. Opposite the door is a small table, and next to it is a big window so I can get the light. Near my bed is a tall wardrobe that I use to hang my clothes, and right next to it is a smaller closet that I store some other things. My room really matches my personality, and I love spending time there.

@trần huy nhật

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giải trên cymath.com í

2^x+3 . 2^x = 144 

2^x+3 . 2^x = 2⁷ + 2⁴

x=4

\(142-\left[50-\left(2^3×10-2^3×5\right)\right]\)

\(=142-\left[50-\left(8×10-8×5\right)\right]\)

\(=142-\left[50-\left(80-40\right)\right]\)

\(=142-\left[50-40\right]\)

\(=142-10\)

\(=132\)

142-[50-(8 x 10 - 8 x5)]

142-{50-[8 x(10-5)}

142-{50-8 x 5}

142-{50-40}

142-10

132

Đặt \(A=100x^2-20x+2y^2+20y-9\)

\(\Rightarrow A=\left(100x^2-20x+1\right)+\left(2y^2+20y+50\right)-60\)

\(=\left(10x-1\right)^2+2\left(y^2+10y+25\right)-60\)

\(=\left(10x-1\right)^2+2\left(y+5\right)^2-60\)

Vì \(\left(10x-1\right)^2\ge0\forall x\), \(2\left(y+5\right)^2\ge0\forall y\)

\(\Rightarrow\left(10x-1\right)^2+2\left(y+5\right)^2-60\ge-60\forall x,y\)

hay \(A\ge-60\)

Dấu " = " xảy ra \(\Leftrightarrow\hept{\begin{cases}10x-1=0\\y+5=0\end{cases}}\Leftrightarrow\hept{\begin{cases}10x=1\\y=-5\end{cases}}\Leftrightarrow\hept{\begin{cases}x=\frac{1}{10}\\y=-5\end{cases}}\)

Vậy \(minA=-60\)\(\Leftrightarrow\hept{\begin{cases}x=\frac{1}{10}\\y=-5\end{cases}}\)

Ta có : Đặt A = 100x² - 20x + 2y² + 20y - 9

= (100x² - 20x + 1 ) + (2y² + 20y + 50) - 60

= [(10x)² - 10x - 10x + 1] + 2(y² - 10y + 25) - 60

= [10x(10x -  1) - (10x - 1)] + 2(y² - 5y - 5y + 25) - 60

= (10x - 1)(10x - 1) + 2[y(y - 5) - 5(y - 5)] - 60

= (10x - 1)² + 2(y - 5)² - 60

Vì \(\hept{\begin{cases}\left(10x-1\right)^2\ge0\forall x\\2\left(y-5\right)^2\ge0\forall y\end{cases}}\Rightarrow\left(10x-1\right)^2+2\left(y-5\right)^2-60\ge-60\)

Dấu "=" xảy ra <=> \(\hept{\begin{cases}10x-1=0\\y-5=0\end{cases}}\Rightarrow\hept{\begin{cases}x=\frac{1}{10}\\y=5\end{cases}}\)

Vậy Min A = -60 <=> x = 1/10 ; y = 5

Cách 1: \(B=\left\{4;5;6;7;8;9;10;11;12;12;14\right\}\)

Cách 2: \(B=\left\{x\in N;3< x< 15\right\}\)

B={4.5,6,7,8,9,10,11,12,13,14}

B={xeN/3<x<15}

do mình ko có gạch thẳng nên dùng xéo

nhanh để mik tích cho

Vận tốc ô tô đi nửa quãng đường sau là: \(10-6=4\)( km/h )

Nửa quãng đường là: \(60:2=30\)( km )

Thời gian đi nửa quãng đường trước là: \(30:10=3\)( giờ )

Thời gian đi nửa quãng đường sau là: \(30:4=7,5\)( giờ )

Thời gian dự định đi quãng đường AB là \(3+7,5=10,5\)( giờ )

Vậy thời gian dự định đi quãng đường AB là \(10,5\)giờ

(3⁸ . 3¹⁶) : (3 ⁷ . 3¹⁴)

3²⁴ : 3²¹

3³

HK TỐT

(3⁸ . 3¹⁶) : (3⁷ . 3¹⁴) = 3⁸⁺¹⁶ : 3⁷⁺¹⁴

                                 = 3²⁴ : 3²¹

                                 = 3^24-21

                                 = 3³ = 27

a) ĐCNN = 0,1 cm

b) ĐCNN = 0,5 cm

c) ĐCNN = 0,5 cm

a/0,1 cm

b/1cm

c/0,5cm

Ta có : A = -(a - b + c) - (-a - b - c)

= -a + b - c + a - b + c

= 0

A = (-a - b + c) - (-a - b - c)

= -a - b + c + a + b + c

= (-a + a) + (-b + b) + (c + c)

= 2c

Vậy A = 2c.