`xy+3x+3y=-16`

`=>(xy+3x)+(3y+9)=-7`

`=>x(y+3)+3(y+3)=-7`

`=>y(y+3)(x+3)=-7`

Lập bảng : 

a)Ta có :\(xy-2x-3y=9\)

\(x.\left(y-2\right)\)-\(3.\left(y-2\right)\)\(-6=9\)

\(\left(x-3\right)\)\(.\left(y-2\right)\)\(=15\)

đến đây cậu tự làm tiếp nhé

x-3 ,y-2 Ư(15)=1;3;5;15

\(\left(x;y\right)\) \(\left(4;17\right),\left(18;3\right),\left(2;-13\right),\left(-12;1\right),\left(6;7\right),\left(8;5\right),\)\(\left(0;-3\right),\left(-2;-1\right)\)

a) x(x-1)=0+12

    x(x-1)=12

    x(x-1)=4.3

=>x=4

a, \(x^2-x-12=0\)

\(x^2+\left(-x\right)+\left(-12\right)=0\)

\(\Delta=-1^2-4.1.\left(-12\right)=1+48=49>0\)

Nên pt có 2 nghiệm phân biệt 

\(x_1=\frac{1-\sqrt{49}}{2.1}=\frac{1-7}{2}=-\frac{6}{2}=-3\)

\(x_2=\frac{1+\sqrt{49}}{2.1}=\frac{1+7}{2}=\frac{8}{2}=4\)

\(\left\{{}\begin{matrix}2xy+x+2y=5\\xy+3x-3y=5\end{matrix}\right.\)

\(\Rightarrow2xy+x+2y=xy+3x-3y\)

\(\Rightarrow2xy+x+2y-xy-3x+3y=0\)

\(\Rightarrow\left(2xy-xy\right)+\left(x-3x\right)+\left(2y+y\right)=0\)

\(\Rightarrow xy-2x+3y=0\)

\(\Rightarrow xy-2x+3y-6=-6\)

\(\Rightarrow x\left(y-2\right)+3\left(y-2\right)=-6\)

\(\Rightarrow\left(x+3\right)\left(y-2\right)=-6\)

Xét ước là xong,mấy câu kia tương tự

bài này của bn giống mk DDT Miner Ter

a: xy+2x-3y=14

=>x(y+2)-3y-6=8

=>(x-3)(y+2)=8

=>(x-3;y+2)∈{(1;8);(8;1);(-1;-8);(-8;-2);(2;4);(4;2);(-2;-4);(-4;-2)}

=>(x;y)∈{(4;6);(11;-1);(2;-10);(-5;-4);(5;2);(7;0);(1;-6);(-1;-4)}

b: 2xy+5y-3x=18

=>y(2x+5)-3x-7,5=18-7,5

=>2y(x+2,5)-3(x+2,5)=10,5

=>(x+2,5)(2y-3)=10,5

=>(2x+5)(2y-3)=21

=>(2x+5;2y-3)∈{(1;21);(21;1);(-1;-21);(-21;-1);(3;7);(7;3);(-3;-7);(-7;-3)}

=>(2x;2y)∈{(-4;24);(16;4);(-6;-18);(-26;2);(-2;10);(2;6);(-8;-4);(-12;0)}

=>(x;y)∈{(-2;12);(8;2);(-3;-9);(-13;1);(-1;5);(1;3);(-4;-2);(-6;0)}