Rewrite the following sentences using the passive voice

1.Our boss has suggested a new idea.

=> A new idea has been suggested by our boss.

2. You mush wash this sweater in warm water.

=> This sweater must be washed in warm water.

3. We sold the last shirt of this style a few hours ago.

=> The last shirt of this style was sold a few hours ago.

4. They built the Eiffel Tower in 1889.

=> The Eiffel Tower was built in 1889.

5. The police are questioning him at their headquarters.

=> He is being questioned by the police at their headquarters .

\(pt\left(1\right)\Rightarrow x>0;\text{ }pt\left(2\right)\Rightarrow y>0\)

\(pt\left(1\right)\Leftrightarrow x^2+2=3xy^2;\text{ }pt\left(2\right)\Leftrightarrow y^2+2=3x^2y\)

\(\Rightarrow x^2+2-\left(y^2+2\right)=3xy^2-3x^2y\)\(\Leftrightarrow\left(x-y\right)\left(x+y\right)+3xy\left(x-y\right)=0\)

\(\Leftrightarrow\left(x-y\right)\left(x+y+3xy\right)=0\)

\(\Leftrightarrow x=y\text{ (do }x+y+3xy>0\text{)}\)

Thay .....

\(x^2+2=3x^3\Leftrightarrow\left(x-1\right)\left(3x^2+2x+2\right)=0\)

\(\Leftrightarrow x-1=0\text{ hoặc }3x^2+2x+2=0\text{ (vô nghiệm)}\)

\(\Leftrightarrow x=1\Rightarrow y=1\)

Kết luận: (x;y) = (1;1).