8 How much do these apples cost?

9 THis is a blue car

11 Are there 40 classrooms in Phong's school?

13 How wide if the Great wall

\(\dfrac{7x-2}{3}-2x< 5-\dfrac{x-2}{4}\)

<=>\(\dfrac{4\left(7x-2\right)}{12}-\dfrac{24x}{12}< \dfrac{60}{12}-\dfrac{3\left(x-2\right)}{12}\)

<=>\(4\left(7x-2\right)-24x< 60-3\left(x-2\right)\)

<=>\(28x-8-24x< 60-3x+6\)

<=>\(28x+3x-24x< 60+8+6\)

<=>\(7x< 74\)

<=>x<\(\dfrac{74}{7}\)

Vậy...

Cạnh BH ở đâu vậy em nhỉ ? 

Yêu cầu đề bài là gì vậy bạn?

Chọn A

A

A

c: \(\Leftrightarrow x^2-5x-x^2-7< =0\)

=>-5x<=7

hay x>=-7/5

d: \(\Leftrightarrow x^2-x-2+3-x^2>=0\)

=>-x+1>=0

=>-x>=-1

hay x<=1

1: \(P=\left(\dfrac{\sqrt{x-2}\left(3-\sqrt{x-2}\right)}{9-x+2}+\dfrac{x+7}{11-x}\right):\left(\dfrac{3\sqrt{x-2}+1-\sqrt{x-2}+3}{\sqrt{x-2}\left(\sqrt{x-2}-3\right)}\right)\)

\(=\dfrac{3\sqrt{x-2}-x+2+x+7}{11-x}:\dfrac{2\sqrt{x-2}+4}{\sqrt{x-2}\left(\sqrt{x-2}-3\right)}\)

\(=\dfrac{3\sqrt{x-2}+9}{11-x}\cdot\dfrac{\sqrt{x-2}\left(\sqrt{x-2}-3\right)}{2\sqrt{x-2}+4}\)

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

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

2: Đặt căn x-2=a(a>=0)

=>P=-3a/(2a+4)

P nguyên

=>-3a chia hết cho 2a+4

=>-6a chia hết cho 2a+4

=>-6a-12+12 chia hết cho 2a+4

=>2a+4 thuộc {1;-1;2;-2;3;-3;4;-4;6;-6;12;-12}

=>a thuộc {1;4}

=>x-2=1 hoặc x-2=16

=>x=3 hoặc x=18

\(\dfrac{4x+3}{5}-\dfrac{6x-2}{7}=\dfrac{5x+4}{3}+3\)

\(\Leftrightarrow21\left(4x+3\right)-15\left(6x-2\right)=35\left(5x+4\right)+3.105\)

\(\Leftrightarrow-6x+93=175x+455\)

\(\Leftrightarrow181x=-362\)

\(\Leftrightarrow x=-2\)

\(\dfrac{4x+3}{5}-\dfrac{6x-2}{7}=\dfrac{5x+4}{3}+3\)\(\Leftrightarrow\dfrac{84x+63}{105}-\dfrac{90x-30}{105}=\dfrac{175x+140}{105}+\dfrac{315}{105}\)

\(\Leftrightarrow84x+63-90x+30=175x+140+315\)

\(\Leftrightarrow84x-90x-175x=140+315-63-30\)

\(\Leftrightarrow-181x=362\)

\(\Leftrightarrow x=-2\)