tim cac so nguyen x,y thoa man:xy+x-y-1=1
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Tim cac so nguyen thoa man (x+y)^2=(x-1)(y+1)
tim cac so nguyen x,y thoa man: 1/x-1/3=1/y voi x,y khac 0
tim cac so huu ti x y thoa man x+y va 1/x +1/y nguyen duong
Tim cac gia tri nguyen cua x biet
a, Y=5x+9/ x+3
b, Tim cac cap so nguyen x , y thoa mai he thuc :
(2x-1).(y+4)
\(a,\) Ta có \(y=\frac{5x+9}{x+3}\)
Để \(y\) nhận giá trị nguyên thì : \(5x+9⋮x+3\)
\(\Rightarrow5\left(x+3\right)+9-15⋮x+3\)
\(\Rightarrow5\left(x+3\right)-6⋮x+3\)
\(\Rightarrow-6⋮x+3\)
\(\Rightarrow6⋮x+3\)
\(\Rightarrow x+3\inƯ_{\left(6\right)}\)
\(\Rightarrow x+3=\left(-6,-3,-2,-1,1,2,3,6\right)\) Máy tớ ko viết được ngoặc khép thông cảm nha
\(\Rightarrow x=\left(-9,-6,-5,-4,-2,-1,0,3\right)\)
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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 x, y thoa man x>y>1 va 2x + 2y + 1 chia het cho xy
Tim cac so nguyen duong thoa man: 1/x+1/y=2/3
Giả sử :
\(x\le y\)(1)
=> \(\frac{1}{x}+\frac{1}{y}\ge\frac{2}{y}\)
=> \(\frac{2}{3}\ge\frac{2}{y}\)
=> \(\frac{1}{3}\ge\frac{1}{y}\Rightarrow3\ge y\)(2)
Lại có :
\(\frac{1}{x}+\frac{1}{y}\le\frac{2}{x}\)
=> \(\frac{2}{3}\le\frac{2}{x}\Rightarrow3\le x\)(3)
Từ (1) , (2) , (3)
=> \(3\le x\le y\le3\)
=> x = y = 3
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Cau 1: Co tat ca bao nhieu so co 3 chu so ma trong moi so co duy nhat 1 chu so 5.
Cau 2: Biet rang 3n+1 va 5n+4 (n thuoc N) la hai so khong nguyen to cung nhau. Khi do UCLN cua 3n+1 va 5n+4 la bao nhieu.
Cau 3: Tim cap (x;y) nguyen am thoa man:xy+3x+2y+6=0 va lxl+lyl=5.
tim cac so nguyen x,y,z thoa man dieu kien sau
x^2=y-1
y^2=z-1
z^2=x-1