biet rang so 691.k la mot so nguyen to

a, Chung minh rang 5m+3 va 3m+2 la 2 so nguyen biet rang 1 so bang 10 ngen to cung nhau voi m la so nguyen to bat ky.

b,Tim 1 bo ba so nguyen to biet rang 1 so bang 10 phan tram tong cua 3 so can tim

Ai lam nhanh nhat minh tick cho

Mot so nguyen to khi chia cho 30 co so du la r.tim r biet rang r khong la so nguyen to?

Tim mot so nguyen to p biet rang p bang tong cua 2 so nguyen to va bang hieu cua hai so nguyen to. 

Giup minh nha cac bn, minh gap lam.

cho biet ; 30*31*32*33*k=66..81440

k la mot so tu nhien thich hop va * la mot so chua biet

vay chu so 8 la...

1) Mot so nguyen to chia cho 30 duoc so du la r.Tim r,biet r khong phai la so nguyen to.

2) Chung minh rang:

a/ So 17 khong viet duoc tong 3 hop so khong bang nhau.

b/Moi so le lon hon 17 deu viet duoc duoi dang 3 hop so khac nhau. 

Cho biet : 30 nhan 31 nhan 32 nhan 33 nhan K = 66*81440

K la mot tu nhien thich hop va * la mot so chua biet . Vay chu so * la ?

tim mot so tu nhien  co 5 chu so biet rang so gom 5 chu so tren viet theo thu tu nguoc lai thi bang 4 lan so phai tim vay so do la

tong hai so nguyen to la mot so nguyen to. Vay hieu hai so nguyen to la..................................