Bài 4 :

xy - x + 2y = 3

x ( y - 1 ) + 2y - 2 = 3 - 2

x ( y - 1 ) + 2 ( y - 1 ) = 1

( y - 1 ) ( x + 2 ) = 1

Xét bảng :

Vậy (x;y) = (-1;2) = (-3;0)

a, xy-x+2y=3

<=>x(y-1)+2(y-1)=1

<=>(x+2)(y-1)=1

\(4,a;xy-x+2y=3\)

\(x\left(y-1\right)+2y-2=1\)

\(x\left(y-1\right)+2\left(y-1\right)=1\)

\(\Rightarrow\left(x+2\right)\left(y-1\right)=1\)

Lập bảng ....

Ta có:

\(M=\frac{101^{102}+1}{101^{103}+1}\)

\(101M=\frac{101^{103}+1+100}{101^{103}+1}=1+\frac{100}{101^{103}+1}\)

Ta lại có:

\(N=\frac{101^{103}+1}{101^{104}+1}\)

\(101N=\frac{101^{104}+1+100}{101^{104}+1}=1+\frac{100}{101^{104}+1}\)

Vì \(\frac{100}{101^{104}+1}< \frac{100}{101^{103}+1}\Rightarrow101N< 101M\Rightarrow N< M\)

có một số khi nhân số bé lên 10 lần thì số đó là

Ta có : \(101M=\frac{101\left(101^{102}+1\right)}{101^{103}+1}=\frac{101^{103}+100+1}{101^{103}+1}=1+\frac{100}{101^{103}+1};\)

\(101N=\frac{101\left(101^{103}+1\right)}{101^{104}+1}=\frac{101^{104}+1+100}{101^{104}+1}=1\frac{100}{101^{104}+1}\)

Vì \(\frac{100}{101^{103}+1}>\frac{100}{101^{104}+1}\Rightarrow1+\frac{100}{101^{103}+1}>1+\frac{100}{101^{104}+1}\Rightarrow101M>101N\)

=> M > N

ta có bổ đề sau .với\(\frac{a}{b}>0\Rightarrow\frac{a}{b}< \frac{a+c}{b+c}\)

\(\Rightarrow N=\frac{101^{103}+1}{101^{104}+1}< \frac{101^{103}+1+100}{101^{104}+1+100}\)

mà \(\frac{101^{103}+1+100}{101^{104}+1+100}=\frac{101^{103}+101}{101^{104}+101}\)

\(=\frac{101\left(101^{102+1}\right)}{101\left(101^{103}+1\right)}=\frac{101^{102}+1}{101^{103}+1}=M\)

vậy \(M>N\)

Ta có: \(N=\frac{101^{103}+1}{101^{104}+1}< \frac{101^{103}+1+100}{101^{104}+1+100}\)

Mà: \(\frac{101^{103}+1+100}{101^{104}+1+100}=\frac{101^{103}+101}{101^{104}+101}=\frac{101\left(101^{102}+1\right)}{101\left(101^{103}+1\right)}=\frac{101^{102}+1}{101^{103}+1}=M\)

Ta có: \(N< \frac{101^{103}+1+100}{101^{104}+1+100};\frac{101^{103}+1+100}{101^{104}+1+100}=M\)

=>  N<M

=>

M>N K CHO MK NHAAAAAAAAAAAAAAAAAAAAAAA

Ta có : 

\(N=\frac{101^{103}+1}{101^{104}+1}< 1=\frac{101^{103}+1+100}{101^{104}+1+100}=\frac{101^{103}+101}{101^{104}+101}=\frac{101\left(101^{102}+1\right)}{101\left(101^{103}+1\right)}=\frac{101^{102}+1}{101^{103}+1}=M\)

Vậy\(N< M\)

Kết quả là:N<M

Ta có :

\(M=\frac{101^2+1}{101^3+1}\)

\(N=\frac{101^3+1}{101^4+1}< 1=\frac{101^3+1+100}{101^3+1+100}=\frac{101^3+101}{101^3+101}=\)\(\frac{101^2\cdot101+101\cdot1}{101^3\cdot101+101\cdot1}=\frac{101\cdot\left(101^2+1\right)}{101\cdot\left(101^3+1\right)}=\frac{101^2+1}{101^3+1}=M\)

\(\Rightarrow M>N\)

\(101\cdot M=\frac{101^{103}+101}{101^{103}+1}=1+\frac{100}{101^{103}+1}\)

\(101\cdot N=\frac{101^{104}+101}{101^{104}+1}=1+\frac{100}{101^{104}+1}\)

mà 101^103+1<101^101+1         =>\(\frac{100}{101^{103}+1}>\frac{100}{101^{104}+1}\)

nên M>N

a/
$xy-x+2y=3$

$\Rightarrow x(y-1)+2(y-1)=1$

$\Rightarrow (x+2)(y-1)=1$

Do $x,y$ nguyên nên $x+2, y-1$ cũng là số nguyên. Mà tích của chúng bằng $1$ nên ta xét các TH sau:

TH1: 

$x+2=1, y-1=1\Rightarrow x=-1; y=2$

TH2: 

$x+2=-1, y-1=-1\Rightarrow x=-3; y=0$

b/

\(101M=\frac{101^{103}+101}{101^{103}+1}=1+\frac{100}{101^{103}+1}> 1+\frac{100}{101^{104}+1}=\frac{101^{104}+101}{101^{104}+1}=101.\frac{101^{103}+1}{101^{104}+1}=101N\)$\Rightarrow M> N$

\(.....^{2014}\)thì lun lun \(>....^{2013}\)rồi

Đặt 10M và 10N rồi làm

Ta có: M =\(\frac{101^{102}+1}{101^{103}+1}=\frac{101^{103}+101}{101^{104}+101}=\frac{101^{103}+1+100}{101^{104}+1+100}\)

Mà    : N = \(\frac{101^{103}+1}{101^{104}+1}\)<    M = \(\frac{101^{103}+1+100}{101^{104}+1+100}\)

\(\Rightarrow N< M\)