Muon chung minh n+3 va 2n+5 la so nguyen to thi ta phai chung minh n+3 va 2n+5 co UC la 1
(2n+5;n+3)=(n+2;n+3)=1 (UC)
Vay 2n+5 va n+3 la hai so nguyen to cung nhau
Cac ban lam dang nay cu lay so lon tru so be nhe!
chung to rang hai so n + 1 va 2n + 3 la hai so nguyen to cung nhau
chung minh rang 2n+3 va 3n+5 la hai so nguyen to cung nhau (n thuoc N*)
Chung to rang hai so 2n+7 va 2n+9 la hai so nguyen to cung nhau
chung minh rang n+1 va 2n+3 la 2 so nguyen to cung nhau
chung to rang 2n + 1 va 2n + 3 ( n\(\in\)N ) la 2 so nguyen to cung nhau
Chung to rang cac so sau la cac so nguyen to cung nhau :
1) 2n + 1 và 2n + 3
2) 2n + 5 va 3n + 7
cho n la so tu nhien bat ki ;chung minh rang (n+3) va(2n+5) la 2 so nguyen to cung nhau
chung to 2 so sau la 2 so nguyen to cung nhau
a,2n+3 va n+2
b,3n+1va 2n+1
c,n+10 va n+11
chung minh rang voi moi so tu nhien n, cac so sau la hai so nguyen to cung nhau:
a) 7n + 10 va 5n + 7
b) 2n +3 va 4n +8