Answer:
Yes, 3 is a primitive root of 7.
Step-by-step explanation:
By definition if primitive root, b is a primitive root of p, where p is a prime, if powers of b includes all residue classes mod p. Here,
[tex]3^0=1[/tex] [tex]3^0[/tex] mod 7=1
[tex]3^1=3[/tex] [tex]3^1[/tex] mod 7=3
[tex]3^2=9[/tex] [tex]3^2[/tex] mod 7=2
[tex]3^3=27[/tex] [tex]3^0[/tex] mod 7=6
[tex]3^4=81[/tex] [tex]3^0[/tex] mod 7=4
[tex]3^5=243[/tex] [tex]3^0[/tex] mod 7=5
And [tex]\phi(7)[/tex]=numbers less than 7 and prime to 7=1,2,3,4,5,6, presents in the residue class of 3 mod 7, this proves 3 is a primitive root of 7.