Các câu hỏi tương tự
a, Neu A la con cua B thi voi moi x thuoc a, ta co x thuoc B
b, De chung to A la con cua B ta phai chung to voi noi X thuoc A thi X thuoc B
c, quy uoc tap hop rong la tap hop con cua moi tap hop
d,de chung to a khong phai tap hop con cua b, chi can neu ra 1 phan tu thuoc a ma khong thuoc b
so nguyen la gi .neu x la so nguyen thi x thuoc tap hop Z kohay tap hop z la tap hop cac so nguyen à
cho ab la 1 P/S . Chung minh neu a/b = a - x / b - y thi a/b=x/y (x , y thuoc Z)
Cho A thuoc {0.1.2.3.4.5.6.7.8.9.10} biet A co hon 1 phan tu neu x,y,z thuoc A va x<y<z thi z =x.y tim A
cho x,y thuoc z hay chung to rang
A neu x-y>0 thy x>y
B neu x>y thi x-y>0
Neu 3-x=-10 thi x co gia tri la
tim gia tri nho nhat cua bieu thuc: A=|x-3|+2,x thuoc Z
cac cau giup voi
cho A = 1/15 nhan 225/(8+2) + 3/14 nhan 196/(3x+6) (x thuoc Z; x khac -2 )
a) Rut gon A
b) Tim x thuoc Z de A thuoc Z
c) trong cac gia tri nguyen A tim gia tri lon nhat va gia tri nho nhat
CHUNG MINH VOI X,Y THUOC N neu x+2y chia het cho 5 thi 3x-4y chia het hco 5 dieu nguoc co dung khong