Chung to rang tong sau khong la so chinh phuong :
A=abc+bca+cab
Cac ban lam on nhanh gium minh voi
a, so co tong cac chu so la 2004 khong la so chinh phuong
b, so co tong cac chu so la 2006 khong la so chinh phuong
c, n = 20044+20043+20042+23 khong la so chinh phuong
1 so chinh phuong co chu so tan cung khong the la chu so nao
A.0
B.6
C.9
D.8
Cac ban co phai la so 0 phai khong?
Cho A=5+5^2+5^3+...+5^2016
a, A la hop so hay so nguyen to
b,A co phai la so chinh phuong khong ?
giup minh giai voi nha cac ban \(\)
bai 1
tinh : 1 + 2 + 3 + ... + 1998 + 1999
bai 2 : tinh tong cua
a) tat ca cac chu so tu nhien co 3 chu so
b) tat ca cac so le ci 3 chu so
bai 3 : tinh tong
a) tat ca cac so : 2 , 5, 8,11, ... , 296
b) tat ca cac so : 7 , 11 ,15 , 19 , ..... , 283
bai 12
cho day so
a) 1 , 4 , 7 , 10 , 13 ,19
b) 5 , 8 , 11 , 14 , 17 , 20 , 23 , 26 , 29
c) 1 , 5 , 9 , 13 , 17 , 21 , ......
hay tim cong thuc bieu dien cac day so tren
mong cac ban lam ho minh minhdang can gap ban nao tra loi dau tien minh se tich ngay lap tuc
Co so chinh phuong nao co tong cac chu so cua no bang 23456 khong ?
cho cac so tu nhien n va 2n co tong cac chu so bang nhau
a) chung minh n chia het cho 9
b)tim so chinh phuong n co 3 chu so biet n chia het cho5 va 2n thi tong cac chu so khong doi
khong gia tri xet xem cac tong sau day co chia het cho 9 hay khong 2*3*4*5*6*7+8*9*10*11*12
cho x =(2n + 1)(3n+2) voi n thuoc N*
hoi tich tat ca cac uoc cua x co phai la so chinh phuong khong? giai thich?