xy + x - y = 6

\(\Rightarrow x\left(y+1\right)-y-1=5\)

\(\Rightarrow x\left(y+1\right)-\left(y+1\right)=5\)

\(\Rightarrow\left(x-1\right)\left(y+1\right)=5\)

Ta có bảng sau: 

x - 1	1	-1	5	-5
y + 1	5	-5	1	-1
z	2	0	6	-4
y	4	-6	0	-2

Vậy...

 => x(y+1) - (y+1) = 5

=> (x-1)(y+1) = 5

sau tự giải nha bn , k mik nữa

Ta có : \(xy+x-y=6\)

         \(\Leftrightarrow xy+x=6+y\)

          \(\Leftrightarrow x\left(y+1\right)=6+y\)

            \(\Rightarrow\left(x-1\right)\left(y+1\right)=5\)

\(\cdot th1:x-1=-1\Rightarrow x=0;y=-6\)

\(\cdot th2:x-1=1\Rightarrow x=2;y=4\)

\(\cdot th3:x-1=-5\Rightarrow x=-6;y=-2\)

\(\cdot th4:x=-1=5\Rightarrow x=6;y=0\)

I live in Tan Phong village and it is my hometown , too . My hometown is a small village but it is very beautiful . It's in the North of Viet Nam . There is a small river around my village . In the summer , children often go here and swim in it . Some fishermen usually catch fish here and take them to the market . There aren't many traffic here but there are many trees here . People are also friendly and kind . In my village , there are many houses such as : two floor houses , one floor house , ... In the morning , the cock is like an alaem clock for everyone . It crow to everyone get up . The life in my village is vey busy . I love my hometown very much because i have many nice memories with it .

a

x²...9y²...x

b

4x²-12xy...3y

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Bài 2: 

b: \(=\left(x-y\right)\left(x+y\right)+\left(x-y\right)=\left(x-y\right)\left(x+y+1\right)\)

1, chỉ cách làm mẫu nek:

NO+O2=>NO2

NO+O2 là vế 1, NO2 là vế 2

vế 1 : N=1, O=3 

vế 2 : N=1, O=2

cân bằng: 

vế 2: 2O2( O vế 2 ít ng tử hơn ) 

lúc này vế 2 có O=4  vàN=2

vế 1: 2NO 

lúc này vế 1 N=2, O=4

kl : 2NO+O2=>2NO2

2 , làm y như nãy:

4P+5O2=>2P2O5

3, Fe2O3+3H2SO4=>Fe(SO4)3+3H2O

b d b b c a

Question 1: B
Question 2: D
Question 3: B
Question 4: B
Question 5: C
Question 6: A