M = 1 + 5 + 52 + 53 + 54 + ... + 52013
5M = 5 + 52 + 53 + 54 + 55 + ... + 52014
5M - M = (5 + 52 + 53 + 54 + 55 + ... + 52014) - (1 + 5 + 52 + 53 + 54 + ... + 52013)
4M = 52014 - 1
4M + 1 = 52014 = (51007)2 là số chính phương
cho M=1+52+53+54+...+52009 chung to rang (4M+1)x22010 la 1 so chinh phuong
a) cho A = 1+3+5+7+...+(2n+1) Voi n thuoc N
chung to rang A la so chinh phuong
b)B=2+4+6+8+...+2n voi n thuocN
so B co phai la so chinh phuong ko
a) cho A = 1 + 3 + 5 + 7 +......+(2n + 1) Voi n thuoc N
chung to rang A la so chinh phuong
b) cho B = 2 +4+6 + 8 + ....+ 2n Voi n thuocN
so B co the la chinh phuong ko
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
chung to rang so A la so chinh phuong biet rang
A = 1+3+5+7+...+(2n-1) voi n € N*
cho bieu thuc
B=5o+51+52+...+52017
a, Chung to 4B +1 la 1so chinh phuong
b,Tim x la so tu nhien,biet 4B+1 =5x+2
chung minh ba la 1 so chinh phuong
B = {1, 3 , 5 ,....,(2k-1)}
cho bieu thuc M= 5+52+53+.....+580chung to rang
a, M chia het cho 6
b, M khong phai la so chinh phuong
Cho A = 5+52+53+...+5100
a)so A la so nguyen to hay hop so
b)so A co phai la so chinh phuong khong?
