M=1111......1 - 222...2
(2n chu so 1) ( n chu so 2)
chung minh M 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 *
2.\(4n^3+14n^2+6n+12=4n^3+2n^2+12n^2+6n+12\)
\(=(2n+1)(2n^2+6n)+12\)\(⋮\)\(2n+1\)
Mấy bước sau bạn làm tiếp nhé.
Cho : A=111...1(2n chu so 1) - 888...8(n so 8)
Chung minh A la so chinh phuong.
Chieu mai nop roi . giup minh nha . Thanks.
chung minh rang neu A la so gom 200 chu so 1 va 100 chu so 2 thi A-B la so chinh phuong
Cho: A,B trong do Agom 2m chu so 1 , B gom m chu so 4
Chung minh rang A+B+C+1 la so chinh phuong
CMR neu A=111...1(200 chu so 1) va B=222...2 (100 chu so 2) thi A-B la mot so chinh phuong
cho so tu nhien a gom 100 chu so va 1 so tu nhien b gom 50 chu so 2 chung minh ava b la hai so chinh phuong
tim so tu nhien N co 2 chu so,biet rang 2N+1 va 3N+1 la cac so chinh phuong
cho m=n^4+2n^3+2n^2+2n+1 chung minh m khong phai la so chinh phuong
giai le mai kiem tra roi can gap lam
chung minh rang: N=444...44 888...8 9(nchu so 4)( n-1 chu so 8) la so chinh phuong