A: Hi, Phong. What are you doing tomorrow?
Phong: I'm going to a book exhibition with my parents.
A: Where is it?
Phong: It’s in Giang Vo Exhibition Centre.
A: How long is it on?
Phong: It’s on from the 14th to the 17th of January.

$3x+x^2=0$

\(\Rightarrow x.\left(3+x\right)=0\) \(\Rightarrow\left[{}\begin{matrix}x=0\\x+3=0\end{matrix}\right.\) \(\Rightarrow\left[{}\begin{matrix}x=0\\x=-3\end{matrix}\right.\) Vậy \(x=0\) hoặc \(x=-3\)

chắc là 120 độ bn ạ

\(27^n.9^n=9^{27}:81\) \(\Rightarrow\left(27.9\right)^n=9^{27}:9^2\) \(\Rightarrow\left(3^5\right)^n=9^{25}\) \(\Rightarrow\left(3^5\right)^n=\left(3^2\right)^{25}\) \(\Rightarrow3^{5n}=3^{50}\) \(\Rightarrow5n=50\) \(\Rightarrow n=10\) Vậy số tự nhiên n là 10

mũ hay nhân zậy bn