2.(\(x^2+y^2\))=1978 \(\Leftrightarrow\left(x^2+y^2\right)=1978\div2\) \(\Leftrightarrow x^2+y^2=989\) (1) ta co \(x^2=989-y^2\rightarrow\) thay vào 1 ta đc ; \(989-y^2+y^2=989\) \(\Rightarrow989=989\) (luôn đúng với mọi x) \(\rightarrow\) vô sô nghiêm
tim x,y thuoc z thoa x^2+xy+y^2=x^2y^2
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
Tim cac gia tri x, y thoa man:
a, ( x2 - 1 ) ( x2 - 16 ) < 0 ca x thuoc z
b, 1/x - y/8 = 1/16 va x, y thuoc N
c, | x+1 | + | x+2 | + | x+3 | = x
timx,y thuoc z thoa x^2+xy+y^2=x^2y^2
tim x,y,z,t thoa man x^2+y^2+z^2+t^2=x(y+z+t)
Tim x ,y thuoc Z : 2^x + 2^y = 72
tim x,y thuoc Z biet 25-y^2=9(x-2018)^2
tim x y thuoc z biet (x+y).2=xy
tim x,y thuoc Z sao cho x^2+y^2=2020
