cho A=2*3*5*7*9*......*Pn la tich cua aso nguyen to dau tien. Chung to rang 3 so A-1;A;A+1 KHONG CO SO NAO LA SO CHINH PHUONG
CMR: P la tich cua n so nguyen to dau tien thi P-1 va P+1 khong la hai so chinh phuong
cho p la tich cua 2016 so nguyen to dau tien
chung minh rang p-1 va p+1 khong la so chinh phuong
cho p la tich 2016 so nguyen to dau tien. chung minh p-1 va p+1 ko phai so chinh phuong
tong cua tich 5 so tu nhien dau tien khac o voi tong 10 so tu nhien dau tien
cho 26 so nguyen,trong do tong cua 5 so bat ki la mot so nguyen duong.chung to rang tong cua 26 so nguyen da ch la mot so nguyen duong.
Cho 31 so nguyen trong do co 5 so bat ki co tong la so nguyen duong.Hay chung to rang tong cua 31 so do deu la so nguyen duong
CMR neu p la tich cua n so nguyen to dau tien (n>1) thi p-1 va p+1 khong the la cac so chinh phuong
giup mk vs nha may bn
bai 1
cho tong : S = 5 + 8 + 11 +14 = ....
a) tim so hang thu 100 cua tong
b) tinh tong 100 so hang dau tien
bai 2
cho tong : S = 7 + 12 + 17 + 22 + .......
a) tim so hang thu 50 cua tong
b) tinh tong 50 so hang dau tien
bai 3
tinh tong cua tat ca cac so hang tu nhien x , biet x la so tu nhien co 2 chu so va 12 < x <91
ban nao lam ho minh 3 bai tren voi ma ban nao nao lam ra dau tien minh se tich ngay va lun