Tim so tu nhien n ,n>2 de 2\(^n\)-1va 2\(^n\)+1 khong dong thoi la so nguyen to
hai so 2^n - 1 va 2^n +1 co the dong thoi la so nguyen to hay dong thoi la hop so duoc khong
chung minh rang hai so 2009^100-1va 2009^100+1 khong dong thoi la so nguyen to
cho n > 2 và không chia hết cho 3 chứng minh rằng 2 số n2 -1 va n2 + 1 khong the dong thoi la so nguyen to
ai giup minh voi
chung to rang 2 so n+1 va 3n+1{n thuoc N} la 2 so nguyen to cung nhau
minh dang can gap...................''''
cho a=1+2+3+...+n v b= 2n+1 (voi n thuoc N , n>hoac bang 2 ) . Chung minh rang a va b 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
Bai tap 1: Cho n thuoc N. Chung minh 4n+9 va n+2 la hai so nguyen to cung nhau?
cho A = 1+2+3+4+...+n va B = 2n + 1 ( voi n thuoc N , n lon hon hoac bang 2) chung minh A va B la hai so nguyen to cung nhau
