Someone sends a text message to his friend on his mobile phone during the New Year, and the number of people who get the text message is also based on the number of people sent by the person plus one

Someone sends a text message to his friend on his mobile phone during the New Year, and the number of people who get the text message is also based on the number of people sent by the person plus one person who sends a text message' after two rounds of text messages. suppose that in the first round, someone sends messages to X people, and X people who get messages send (x+1) messages to each other,

from the meaning of the question,

x+x(x+1)=35,

arranging x2+2x-35=,

getting x1 =.