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a) \(xy+3x-2y-11=0\)
\(x\left(y+3\right)-2y-6-5=0\)
\(x\left(y+3\right)-2\left(y+3\right)=5\)
\(\left(x-2\right)\left(y+3\right)=5\)
\(x-2;y+3\in U\left(5\right)\)
x-2 | 1 | -1 | 5 | -5 |
y+3 | 5 | -5 | 1 | -1 |
x | 3 | 1 | 7 | -3 |
y | 2 | -8 | -2 | -4 |
b) \(xy+2x+y+11=0\)
\(x\left(y+2\right)+y+2+9=0\)
\(x\left(y+2\right)+\left(y+2\right)=-9\)
\(\left(x+1\right)\left(y+2\right)=-9\)
\(x+1;y+2\in U\left(-9\right)\)
x+1 | 1 | -1 | 3 | -3 | 9 | -9 |
y+2 | -9 | 9 | -3 | 3 | -1 | 1 |
x | 0 | -2 | 2 | -4 | 8 | -10 |
y | -11 | 7 | -5 | 1 | -3 | -1 |
a) $xy+3x-2y-11=0$$x\left(y+3\right)-2y-6-5=0$$x\left(y+3\right)-2\left(y+3\right)=5$$\left(x-2\right)\left(y+3\right)=5$$x-2;y+3\in U\left(5\right)$
b) $xy+2x+y+11=0$
$x\left(y+2\right)+y+2+9=0$$x\left(y+2\right)+\left(y+2\right)=-9$$\left(x+1\right)\left(y+2\right)=-9$$x+1;y+2\in U\left(-9\right)$
x-2 | 1 | -1 | 5 | -5 | ||
y+3 | 5 | -5 | 1 | -1 | ||
x | 3 | 1 | 7 | -3 | ||
y | 2 | -8 | -2 | -4 | ||
x+1 | 1 | -1 | 3 | -3 | 9 | -9 |
y+2 | -9 | 9 | -3 | 3 | -1 | 1 |
x | 0 | -2 | 2 | -4 | 8 | -10 |
y | -11 | 7 | -5 | 1 |
a) \(xy+x+2y=5\\ \Rightarrow y\left(x+2\right)+x+2=5+2\\ \Rightarrow\left(x+2\right)\left(y+1\right)=7\)
Ta xét bảng:
x+2 | 1 | 7 | -1 | -7 |
x | -1 | 5 | -3 | -9 |
y+1 | 7 | 1 | -7 | -1 |
y | 6 | 0 | -8 | -2 |
Vậy \(\left(x;y\right)\in\left\{\left(-1;6\right);\left(5;0\right);\left(-3;-8\right);\left(-9;-2\right)\right\}\)
b) \(xy-3x-y=0\\ \Rightarrow x\left(y-3\right)-y+3=3\\ \Rightarrow\left(y-3\right)\left(x-1\right)=3\)
Ta xét bảng:
x-1 | 1 | 3 | -1 | -3 |
x | 2 | 4 | 0 | -2 |
y-3 | 3 | 1 | -3 | -1 |
y | 6 | 4 | 0 | 2 |
Vậy \(\left(x;y\right)\in\left\{\left(2;6\right);\left(4;4\right);\left(0;0\right);\left(-2;2\right)\right\}\)
c) \(xy+2x+2y=-16\\ \Rightarrow x\left(y+2\right)+2y+4=-12\\ \Rightarrow\left(y+2\right)\left(x+2\right)=-12\)
Ta xét bảng:
x+2 | 1 | 2 | 3 | 4 | 6 | 12 | -1 | -2 | -3 | -4 | -6 | -12 |
x | -1 | 0 | 1 | 2 | 4 | 10 | -3 | -4 | -5 | -6 | -8 | -14 |
y+2 | -12 | -6 | -4 | -3 | -2 | -1 | 12 | 6 | 4 | 3 | 2 | 1 |
y | -14 | -8 | -6 | -5 | -4 | -3 | 10 | 4 | 2 | 1 | 0 | -1 |
Vậy \(\left(x;y\right)\in\left\{\left(-1;-14\right);\left(0;-8\right);\left(1;-6\right);\left(2;-5\right);\left(4;-4\right);\left(10;-3\right);\left(-3;10\right);\left(-4;4\right);\left(-5;2\right);\left(-6;1\right);\left(-8;0\right);\left(-14;-1\right)\right\}\)
Giải
Theo đề bài, ta có: \(xy-3x+2y-11=0\)
\(\Leftrightarrow x\left(y-3\right)+2y-6=5\)
\(\Leftrightarrow x\left(y-3\right)+2\left(y-3\right)=5\)
\(\Leftrightarrow\left(x+2\right)\left(y-3\right)=5\)
\(\Leftrightarrow\hept{\begin{cases}x+2\\y-3\end{cases}}\inƯ\left(5\right)=\left\{\pm1;\pm5\right\}\)
Lập bảng:
\(x+2\) | \(1\) | \(-1\) | \(5\) | \(-5\) |
\(y-3\) | \(5\) | \(-5\) | \(1\) | \(-1\) |
\(x\) | \(-1\) | \(-3\) | \(3\) | \(-7\) |
\(y\) | \(8\) | \(-2\) | \(4\) | \(2\) |
Vậy \(\left(x,y\right)\in\left\{\left(-1,8\right);\left(-3,-2\right);\left(3,4\right);\left(-7,2\right)\right\}\)
xy+3x-2y=11
=>x(y+3)-2y-6=5
=>x(y+3)-(2y+6)=5
=>x(y+3)-2(y+3)=5
=>(x+2)(y+3)=5
Bạn kẻ bảng ra nha
\(xy+3x-2y=11\)
\(\Leftrightarrow x\left(y+3\right)-2\left(y+3\right)=5\)
\(\Leftrightarrow\left(x-2\right)\left(y+3\right)=5\)
\(\Rightarrow\left(x-2\right);\left(y+3\right)\)là các ước nguyên của 5
\(Th1:x-2=1\Leftrightarrow x=3\)
\(y+3=5\Leftrightarrow y=3\)
\(Th2:x-2=-1\Leftrightarrow x=-1\)
\(y+3=-5\Leftrightarrow y=-8\)
\(Th3:x-2=5\Leftrightarrow x=7\)
\(y+3=1\Leftrightarrow y=1\)
\(Th4:x-2=-5\Leftrightarrow x=-3\)
\(y+3=-1\Leftrightarrow y=-4\)
Vậy: \(\left(x;y\right)\in\left\{3,2\right\};\left\{1,-8\right\};\left\{7;-2\right\};\left\{-3;-4\right\}\)
a) x+xy+y=9
=> x(1+y) +y+1=10
=> (x+1)(y+1)=10
Nếu \(x\ge y\)thì \(x+1\ge y+1\)
Từ đó,ta có bảng
x+1 | 10 | 5 | -1 | -2 |
y+1 | 1 | 2 | -10 | -5 |
x | 9 | 4 | -2 | -3 |
y | 0 | 1 | -11 | -6 |
Vậy ( x;y) lần lượt là : (9;0),(0;9),(4;1),(1;4),(-2;-11),(-11;-2),(-3;-6),(-6;-3)
a)\(x+xy+y=9\)
\(\Rightarrow x\left(1+y\right)+y+1=10\)
\(\Rightarrow\left(x+1\right)\left(y+1\right)=10\)
Nếu \(x\ge y\)thì \(x+1\ge y+1\)
Từ đó, ta có bảng như sau:
x+1 | 10 | 5 | -1 | -2 |
y+1 | 1 | 2 | -10 | -5 |
x | 9 | 4 | -2 | -3 |
y | 0 | 1 | -11 | -6 |
Vậy x; y lần lượt là: (9; 0); (0; 9); (4; 1); (1; 4); (-2; -11); (-11; -2); (-3; -6); (-6; -3).