A,
Ta co :
\(\left(2n+3\right)\) la boi cua 4 \(\Rightarrow4⋮\left(2n+3\right)\)
vi 2n+3 \(\ge3\text{}\text{}\text{ và n }\in N\)
Nen 2n+3 thuoc {1:4}
Ta co
+) 2n+3=1
2n =3-1
2n =2
n =2:2
n = 1
+) 2n+3=4
2n =4-3
2n =1
n =1:2 ( vi n thuoc N nen TH nay bi loai )
Vay n= 1