T
thuan_1999_6a


bai 1: cho n thuoc Z
a. Viet tich n.[n+1].[n+2] thanh tong cac luy thua
b. Tong n/3+n^2/2+n^3/6 co phai la so nguyen
bai 2:Chung to cac phan so sau toi gian voi n thuoc Z
a. 2n+2/6n+5 b. 2n+3/4n+7 c. 3n+2/5n+3



:confuse
a. Viet tich n.[n+1].[n+2] thanh tong cac luy thua
b. Tong n/3+n^2/2+n^3/6 co phai la so nguyen
bai 2:Chung to cac phan so sau toi gian voi n thuoc Z
a. 2n+2/6n+5 b. 2n+3/4n+7 c. 3n+2/5n+3