Ta có:

(1² +3*1+3)=1+3+3=7

(2*1-1)=2-1=1

7:1=7

Suy ra n=1

Last week, I went to Sao Beach with my family. That's was a fantastic place. The sand is white and smooth. Water is crysral-clear. There are many fish. We was swimming in that beach. It's so cool. I want to come that again.