nếu:\(|x|=0\Rightarrow x=0\)
\(|x|>0\Rightarrow x>0\)
vây \(|x|\ge0\)
nếu:\(|x|=0\Rightarrow x=0\)
\(|x|>0\Rightarrow x>0\)
vây \(|x|\ge0\)
cho a la mot so nguyen .Chung to rang :a2 lon hon hoac bang 0;-a2 be hon hoac bang 0
cho6 so tu nhien khac nhau co tong la 50.chung minh rang trong 6 so tu nhien da cho ton tai 3 so co tong lon hon hoac bang 30
chung to rang hieu ab -ba (voi a lon hon hoac bang b ) bao gio cung chia het cho 9
Hai so tu nhien a va b chia cho m co cung so du , a lon hon hoac bang b . chung to rang a- b:m
chung minh rang moi so nguyen to lon hon 2 deu viet duoc duoi dang 4n+1 hoac 4n+3
Tim x biet:
A. (x-3/4).(3x+1/2)lon hon hoac bang 0
B. (2x+1).(4x+3)be hon hoac bang 0
tim so tu nhien n biet rang:
411.2511 lon hon hoac bang 2n.5n lon hon hoac bang 2012.512
Chung minh rang trong 3 so nguyen to lon hon 3 luon co 2 so nguyen to ma tong hoac hieu cua chung chia het cho 12
hay viet cac tap hop sau bang cach khac
A={ 9;11;13;...;99]
B={ 12 ; 24 ; 36 ;48}
M= { THANG 4 ; THANG 6 ;THANG 9 ; THANG 11}
N = { X THUOC N / X LON HON HOAC BANG 3 , LON HON HOAC BANG 10}
Q = { X THUOC N / X LON HON 0 ,BE HON 10}