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I. Rewrite the sentences, use the verbs in present passive form.

1. People can use milk for making butter and cheese.
=> Milk can be used for making butter and cheese.

2. The milkman brings bottles of milk to houses.
=> Bottles of milk are brought to houses by the milkman.

3. Careless driving causes many accidents.
=> Many accidents are caused by careless driving.

4. Weeds cover the river banks.
=> The river banks is covered by weeds.

5. People speak English all over the world.
=> English is spoken all over the world.

6. They don't use the house very often.
=> The house is not used very often.

7. Do they speak French in this school?
=> Is French spoken in this school?

8. They make a lot of beautiful toys from recycled plas
=> A lot of beautiful toys are made from recycled plas.

9. The workers clean the streets everyday
=> The streets are cleaned by the workers everyday.

1. People can use milk for making butter and cheese.
=> Milk can be used for making butter and cheese.

2. The milkman brings bottles of milk to houses.
=> Bottles of milk are brought to houses by the milkman.

3. Careless driving causes many accidents.
=> Many accidents are caused by careless driving.

4. Weeds cover the river banks.
=> The river banks is covered by weeds.

5. People speak English all over the world.
=> English is spoken all over the world.

6. They don't use the house very often.
=> The house is not used very often.

7. Do they speak French in this school?
=> Is French spoken in this school?

People can recycle tires to make pipes or floor coverings

→ Tires can be recycled to make pipes or floor coverings.

\(ĐKXĐ:x\ge0\)

\(\sqrt{P}< \frac{1}{2}\Leftrightarrow P< \frac{1}{4}\Leftrightarrow\frac{\sqrt{x}-2}{\sqrt{x+1}}< \frac{1}{4}\Leftrightarrow\frac{\sqrt{x}-2}{\sqrt{x}+1}-\frac{1}{4}< 0\)

\(\frac{4\left(\sqrt{x}-2\right)}{4\left(\sqrt{x}+1\right)}-\frac{\sqrt{x}+1}{4\left(\sqrt{x}+1\right)}< 0\Leftrightarrow\frac{4\sqrt{x}-8-\sqrt{x}-1}{4\left(\sqrt{x}+1\right)}< 0\)

\(\Leftrightarrow\frac{3\sqrt{x}-9}{4\left(\sqrt{x}+1\right)}< 0.\). Vì \(\sqrt{x}\ge0\forall x\Rightarrow\sqrt{x}+1\ge1>0\forall x\Leftrightarrow4\left(\sqrt{x}+1\right)>0\forall x\)

\(\Rightarrow3\sqrt{x}-9< 0\Leftrightarrow3\sqrt{x}< 9\Leftrightarrow\sqrt{x}< 3\Leftrightarrow x< 9\)

Kết hợp \(ĐKXĐ:x\ge0\Rightarrow0\le x< 9\) 

Vậy.....

em cảm ơn ạ!

Giữ nguyên chiều rộng và gấp chiều dài lên 4 lần, thì chiều dài mới gấp chiều dài ban đầu 4 lần. Coi chiều dài ban đầu là 1 phần, chiều dài mới là 4 phần như thế. Ta có sơ đồ như hình vẽ.

Chiều dài ban đầu của hình chữ nhật đó là:

(51 – 6) : 3 = 15 (m)

Chiều rộng hình chữ nhật đó là:

(15 – 6 = 9 (m)

Chu vi hình chữ nhật đó là:

(15 + 9 ) × 2 = 48 (m)

Diện tích hình chữ nhật đó là:

15 × 9 = 135 $\left(m^2\right)$

Đáp số: Chu vi: $48m$;

               Diện tích: $135m^2$.

Bạn Phương đây biết nhiều bài quá.

xét vế trái 

\(\sqrt{x-2}\)\(+\sqrt{10-x}\)\(=< \sqrt{2\left(x-2+10-x\right)}\)\(=< 4\)

=> vp=<4 

=>\(x^2-12x+40=< 4\)

=> \(\left(x-6\right)^2=< 0\)

=> xảy ra dấu = <=> x=6 

vậy pt có nghiệm là 6 

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