1/

1. C

2. A

3. C

4. B

5. B

2/

1. B

2. A

3. A

4. B

5. A

There used to be fewer unemployed people in this city than now.

Toán hình dễ hơn toán đại đó

worn out

1. I haven't cut my hair since i met her.

2. The last time i saw him was 8 days ago.

3. has been

4. didn't spend

D. It is a fact that

1.If we recycle more, we will help the earth.

2. Factoties won't dump waste  into the rivers if the government fines them heavy.

3. If people travel to work by bus,  there will be fewer cars fumes.

4. We will save thousands of trees if we don't waste paper.

5. If we use waste water carefully, more peope will have fresh water.

6. If you were the president, what would you do?

7. They get sick so often. If they exercise more, they will be healthier.

8. If I had one million  US dolars, I would buy more parks in our city.

9. Ngoc’s mother is unhappy. If Ngoc tidied her room every day, her mother wouldn't be so upset.

10. there isn’t  a garden  at our house. If there were , we would grow vegetables.

5 N

\(a\))\(3x-15=2x\left(x-5\right)\)

\(\Leftrightarrow3\left(x-5\right)-2x\left(x-5\right)=0\)

\(\Leftrightarrow\left(x-5\right)\left(3-2x\right)=0\)

\(\Leftrightarrow\left[{}\begin{matrix}x-5=0\\3-2x=0\end{matrix}\right.\)

\(\Leftrightarrow\left[{}\begin{matrix}x=5\\x=\dfrac{3}{2}\end{matrix}\right.\)

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

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

\(\Leftrightarrow\left(x+2\right)3x=0\)

\(\Leftrightarrow\left[{}\begin{matrix}x+2=0\\3x=0\end{matrix}\right.\)

\(\Leftrightarrow\left[{}\begin{matrix}x=-2\\x=0\end{matrix}\right.\)

\(|x|-1=5\)

⇔\(|x|=6\)

⇔\(\left[{}\begin{matrix}x=6\\x=-6\end{matrix}\right.\)