Các câu hỏi tương tự
Cmr A=1+3+5+...+n la so chinh phuong?
)Cho A= 111...1555...56 ( n chu so 1 , n-1 chu so 5 ) . Cmr : A la so chinh phuong
Cho n thuoc N va n-1 khong chia het cho 4
CMR : 7^n +2 khong la so chinh phuong
cho 1 so chinh phuong co 4 chu so. Biet rang chu so tan cung cua no la so nguyen to, tong cac chu so cua no cung la so chinh phuong va can bac 2 cua no co tong cac chu so cung la so chinh phuong
Jup 2 bai nay 3 tich ( 24 diem hoi dap roi ) ( Lam dc 1 cau 2 tik )
1. CMR
A= 111...1111 - 222....2222 La so chinh phuong
(2n chu so 1) (n chu so 2)
2. CMR
\(4.n^3+14.n^2+6n+12⋮2n+1\)
Voi moi n thuoc Z *
Chung minh rang neu n la mot stn lon hon 1 thi so 2^n-1 khong the la so chinh phuong
biet a+1 va 2a+1 (a thuoc N) dong thoi la 2 so chinh phuong. chung minh rang a chia het cho 24
Tim so tu nhien n co hai chu so biet rang hai so (2n+1) va (3n+1) dong thoi la so chinh phuong.
chung minh rang: N=444...44 888...8 9(nchu so 4)( n-1 chu so 8) la so chinh phuong