\(x-y=x^3-y^3\Leftrightarrow x-y=\left(x-y\right)\left(x^2+xy+y^2\right)\Leftrightarrow\left(x-y\right)\left(x^2+xy+y^2-1\right)=0..\)
\(\Leftrightarrow\orbr{\begin{cases}x-y=0\\x^2+xy+y^2=1\end{cases}.}\) Vì x và y dương nên xy >0 Do đó từ x2 + y2 + xy = 1 Suy ra : x2 + y2 < 1
Tim tat ca cac so nguyen x,y thoa man x^2 + 8y^2 - 6y - 2x + 6y + 6 = 0. ai biet giai giup minh voi,toan nang cao lop 9 do,cam on moi nguoi nhieu
a)Tim tat ca cac so nguyen duong x, y , z thoa man: \(\frac{x+y\sqrt{2013}}{y+z\sqrt{2013}}\)la so huu ti, dong thoi x2 + y2+ z2 la so nguyen to.
b) Tim so tu nhien x, y thoa man: x(1+x+x2) = y(y-1).
tim cac so nguyen duong x;y;z thoa man \(3x^2-18y^2+2z^2+3y^2z^2-18x=27\)
Cho x;y la hai so duong thay doi. Tim gia tri nho nhat cua bieu thuc:
S=(x+y)^2/x^2+y^2. + (x+y)^2/xy
Giai chi tiet giup mk nha!! Cam on!
cho cac so duong x,y thoa x - y = x^3 + y^3. CM x^2 + y^2 < 1
a)Tim cap (x,y) nguyen duong thoa man xy=3(y-x)
b)cho 2 so x,y >0 thoa man x+y = 1
Tim GTNN cua M=(x^2+1/y^2)(y^2+1/x^2)
cho cac so thuc duong x,y thoa man x+y<=3.Tim GTNN cua 1/5xy + 5/x+2y+5
tim cac so nguyen x,y thoa man:x^3+2x^2+3x+2=y^3
tim hai so nguyen duong x,y thoa man x3 +7x = y3 +7y