Viet 16 so co gia tri bat ki la 1;2;3;4 ghep thanh tung cap duoc 8 so.C/M ton tai 2 cap so mo tong cac chu so = nhau ?

Tren bang cua 1 lop hoc co viet cac so:1;2;3;....; 2011;2012;2013.1 hoc sinh tien hanh 1 cong viec nhu sau:Xoa 2 so bat ki trong cac so do roi viet thay vao gia tri tuyet doi cua hieu 2 so da xoa,sau do lap lai cong viec tren cho den khi tren bang chi con lai 1 so.CMR so cuoi cung con lai khong the la so 0.

co ton tai khong 30 so nguyen viet thanh hang ngang ma tong 5 so lien tiep bat ki la so am ,tong 7 so nguyen lien tiep bat ki duong

trên bảng viết 99 số :1,2,3,4,...,99. cu moi lan nguoi ta xoa di hai so bat ki , roi lai viet gia tri cua tong hai so vua xoa vao bang  cuoi cung tren bang chi con lai mot so , gia su so do la k . hay tim k va chung to k khong phai la so chinh phuong

Voi 2 chu so V va X so la ma lon nhat co the viet duoc co gia tri trong he thap phan la

voi 2 chu so la ma 1 va 5(so la ma) so la ma lon nhat co the viet dc
(moi chu so co the dung nhieu lan hoac ko dung)

co gia tri tuog ung trog he thap phan la

tu 200 so tu nhien 1 ,2 ,3 , ... , 200 ta lay ra k so bat ki sao cho trong cac so vua lay luon tim dc 2 so ma so nay la boi cua so kia . tim gia tri nho nhat cua k 

bai 1

cho bieu thuc A = 5/n+1 voi N THUOC Z

a, de A la phan so thi n co dieu kien gi ?

b , tim tat ca cac gia tri nguyen cua n de gia tri A la 1 so nguyen ?

bai 2

cho bieu thuc M = 6/n-3 voi n thuoc Z .Co bao nhieu gia tri cua n de :

a, M ko phai la phan so

b , M la phan so va cp gia tri nguyen ?

bai 3 viet tap hop cacs so nguyen sao cho :

-12/4 < x <6/3

chu so 16 trong so 12,165 co gia tri la