My best friend

To me,one of my best friends is Lan,Lan and I are the same age but she looks older than me because she is very thoughful and well-developed.She has long black hair,a flat nose and bright eyes.She is intelligent and sociable.She is very-hearted and friendly.She always gets on well with everyone,she usually spends her free time on her study and her favorite books.I like her very much because she is always ready to help me with my study.I really admire her and learn alot from her

Question

1 what does Lan look like ?

2 Does she get on well with everyone ?

3 what does Lan usually do in her free time?

The desription of my room

This is my room,there is a desk on the left of the room.On the desk there are many folders,and above the desk there is a bookshelf.There is a bed near the desk.On the right side of the room,there is a window.There is a wardrobe beside the window.The wardrobe is opposite the desk

Question

1 what is there on the left of the room ?

2 what are there on the right?

3 what is there beside the window?

a) \(x^4+2x^3-2x^2+2x-3=0\)

  \(\Leftrightarrow x^4-x^3+3x^3-3x^2+x^2-x+3x-3=0\)

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

 \(\Rightarrow\orbr{\begin{cases}x-1=0\\x^3+3x^2+x+3=0\end{cases}}\)

\(\Leftrightarrow\orbr{\begin{cases}x=1\\\left(x+3\right)\left(x^2+1\right)=0\left(1\right)\end{cases}}\)

Giải (1) : \(\left(x+3\right)\left(x^2+1\right)=0\)

\(\Leftrightarrow\orbr{\begin{cases}x+3=0\\x^2+1=0\end{cases}}\)

\(\Leftrightarrow\orbr{\begin{cases}x=-3\\x^2=-1\end{cases}}\)

Mà \(x^2\)>0

\(\Rightarrow\)pt vô nghiệm

Vậy \(x\in\left(-3;1\right)\)

\(\)