cho x,y thuoc R khac 0 thoa man 2x^2 + y^2/4 +1/x^2 = 4. tim gtnn gtln cua A= 2008+xy

Chung minh bieu thuc Q=(x^4*y^n+1-1/2*x^3*y^n+2):1/2x^3*y^n-20x^4*y:5*xy^2 (n thuoc N) luon <0 voi moi gia tri x khac 0,y khac 0

tim x;y thuoc Z:biet x+5=y.(x-2) x khac 2

cho x , y thuoc Q , y khac 0 

tim x,y sao cho x +y = x.y = x:y

Bai1 : Tim max voi x thuoc [1;3]

F(x) = (x-1)(3-x)

G(x)=(2x-1)(3-x)

Bai2: cho a,b>0 thoa man 4/a+1/b=1

Tim min p=a+b

Bai3: cm Voi moi a>0 ta co a^2(1-2a)<=1/27

Bai4: cho a,b,c >0 tm ab+bc+ca=3

Cm a^3+b^3+c^3>=3

Bai5: x,y,z>0 tm xyz=1

Cm x^2\1+y +y^2\1+z + z^2\1+x

tim hai so x va y biet x^2+y^2;x^2-y^2 va x^2.y^2 ti le nghich voi 1/25,1/7 va 1/576(x khac 0 va y khac 0)

tim cac gia tri x y thoa man 

a,(x^2-1)(x^2-16)<0 va x thuoc Z

B,1/x-y/8=1/16 va x y thuoc N

1 tim x,y,z biet 

\(\frac{-4}{x}=\frac{y}{-14}=\frac{12}{21}=\frac{z}{-63}\)

2 tim n thuoc z n khac 0

a \(\frac{1111100:n}{23331:n}+\frac{-10}{-21}\)

b \(\frac{1075:n}{600:n}=\frac{43}{24}\)

tim x,y thuoc N, biet x.y+2.x+y-13=0