a p+2 va p+ 10
- Neu p = 2 thi p+ 2 = 2+2 =4 la hop so
- Neu p=3 thi p+2 = 2+3 =5 la so nguyen to
p+10 = 3+ 10 la so nguyen to
⇒p=3 thoa man
-Neu p > 3 thi p=3k+1 hoac p=3k+2 [ k ∈N*]
+> Voi 3k+1 ta co :
p+10= 3k + 1 +10=3k+11ko chia het cho 3
⇒p+10la so nguyen to
⇒p+10la so nguyen to
+> Voi p=3k+2 ta co:
p+10 = 3k+2+10=3k+12
vay p =3
bn lam tuong tu voi cac phan kia nha
