vi tong cua so so nguyen to la 894 nen trong 3 so do co it nhat la 1 chu so chan. Ma so nguyen to chan duy nhat la 2 va cung la so nguyen to be nhat nen so nguyen to nho nhat la 2.
Ta co the thay rang trong moi truong hop ma tong cua 3 so nguyen to la so chan thi so nguyen to nho nhat luon la 2
cho toi hoi trong cac so 58,59,61,63 so nao chua thua so nguyen to nho nhat
tong so hat trong nguyen tu X là 28, trong do so hat ko mang dien chiem xap xi 35%. xac dinh X va cho biet X la nguyen to nao
Tim n nho nhat de n^3-4n^2+4n-1 la so nguyen to
CMR
neu p va \(p^2+8\)la so nguyen to thi \(p^2+2\)cung la so nguyen to
neu p va \(8p^2+1\) la so nguyen to thi 2p+1 cung la so nguyen to
Bai 10. Chung minh rang:
a) Neu p va p2+8 la cac so nguyen to thi \(p^2+2\)cung la so nguyen to
b) Neu p va 8.p2+1 la cac so nguyen to thi 2.p+1 cung la so nguyen to
Lam nhanh cho minh nha, minh dang can lam gap
1) Chung minh tong hai so nguyen to la mot hop so
VD: 3+5=8
2) Phan tich da thuc 4x2-a2+y2-16b2+4xy+8ab thanh nhan tu
3) Gia tri nho nhat cua bieu thuc M= (x-1)(x+5)(x2+4x+5) la ...
tim so nguyen to p sao cho p2+2p la so nguyen to
tim so nguyen n de gtri bieu thuc sau la so nguyen to: 3n3-5n2+3n-5
hop chat A co cong thuc phan tu la \(M_2X\). Tong so hat mang dien nhieu hon so hat ko mang dien la 116 , trong do tong so hat mang dien nheu hon tong so hat ko mang dien la 36 . Nguyen tu khoi cua X lon hon nguyen tu khoi cua M la 9 . Tong so hat trong nhuyen tu X nhieu hon tong so hat trong nguyen tu M la 14 . Xac dinh cong thuc phan tu cua A
