tim tat ca cac bo so nguyen to a,b,csao cho abc<ab+bc+ca
n+1; n+3; n+7; n+9; n+13; n+15; n+19 deu la so nguyen to.
Tim so tu nhien n sao cho:
a/ 5:n+1 b/ 15:n+1 c/ n+3 : n+1 d/ 4n+3:2n+1
Biet rang 7a+2b chia het cho 13 ( a,b thuoc N ). Chung to rang 10a+b cung chia het cho 13 ?
Cho p la mot so nguyen to.Chung minh rang 2 so 8p-1 va 8p+1khong dong thoi la so nguyen to
ko phai tinh mot so xem so do co la so nguyen to hay ko
Cho H=111...1(2012 chu so 1)
Hoi H la so nguyen to hay hop so?
a,so 102010+8 chia het cho 9 ko?vi sao
b,tong 2100.7.11+381.13.14 la so nguyen to hay hop so?(giai thich)
ai nhanh cho nghin like
cho p la so nguyen to
Chung to : p.(p-1) .(p+1) chia het cho 6
Cho P = \(\frac{n+4}{2n+1}\)(n ∈ Z) . Tìm cac gia trị của n để P la số nguyên tố
