b: \(B=\dfrac{3y+5}{y-1}-\dfrac{-y^2-4y}{y-1}+\dfrac{y^2+y+7}{y-1}\)

\(=\dfrac{3y+5+y^2+4y+y^2+y+7}{y-1}\)

\(=\dfrac{2y^2+8y+12}{y-1}\)

a) (x - 1)(y + 2) = 7

=> (x-1)\(\in\)Ư(7)={1;7 ; -1; -7}

Nếu x-1= 1 thì x= 1+1 => x=2

Nếu x-1= 7 thì x= 7+1=> x=8

Nếu x-1= -1 thì x= -1+1 => x= 0

Nếu x-1= -7 thì x= -7+1 => x= -6

Sau đó bn thay x r tính xong đó tự tìm y+2 nha

2.

a. 3x(12x - 4) - 9x(4x - 3) = 30

<=> 36x² - 12x - 36x² + 27x = 30

<=> 36x² - 36x² - 12x + 27x = 30

<=> 15x = 30

<=> x = 2

b. x(5 - 2x) + 2x(x - 1) = 15

<=> 5x - 2x² + 2x² - 2x = 15

<=> -2x² + 2x² + 5x - 2x = 15

<=> 3x = 15

<=> x = 5

a) x² ( 5x³ - x - 2323x²y=  6969x³y²- 2323x⁴y+ 2323x²y²

c) x² ( 4x^{3 -} 5xy + 2x ) ( -

$a)$ \(x^{12}:\left(-x\right)^6\)

\(=x^{12}:x^6\)

\(=x^{12-6}\)

\(=x^6\)

$b) $ \(\left(-x\right)^7:\left(-x\right)^5\)

\(=\left(-x\right)^{7-5}\)

\(=\left(-x\right)^2\)

\(=x^2\)

$c)$ \(5x^2y^4:10x^2y\)

\(=\dfrac{1}{2}y^3\)

$e)$ \(\left(-xy\right)^{14}:\left(-xy\right)^7\)

\(=\left(-xy\right)^{14-7}\)

\(=\left(-xy\right)^7\)

Các câu còn lại tương tự nha bạn!

a,x¹² : (-x)⁶ = x¹² : x⁶ =x^12-6 = x⁶

b,-x⁷ : -x⁵ = x⁷ : x⁵ = x^7-5= x²

c,5x³y⁴ : 10x²y = (5 : 10)(x³ : x²)(y⁴: y) = \(\dfrac{1}{2}\)xy³

d,\(\dfrac{3}{4}\)x³y³ : \(\dfrac{-1}{2}\)xy² = (\(\dfrac{3}{4}\): -\(\dfrac{1}{2}\))(x³ : x)(y³ : y²)= -\(\dfrac{3}{2}\)x²y

e,(-xy)¹⁴ : (-xy)⁷ = (-xy)^14-7 = (-xy)⁷

f, câu này đề bài sai đó bn

g(3x²y² - 6x²y + 12xy) : 3xy

= 3xy(xy - x + 4) : 3xy

= xy - x + 4

\(a,\left(x^3+5x^2-2x+1\right)\left(x-7\right)\\ =x^4-7x^3+5x^3-35x^2-2x^2+14x+x-7\\ =x^4-2x^3-37x^2+15x-7\\ b,\left(2x^2-3xy+y^2\right)\left(x+y\right)\\ =2x^3+2x^2y-3x^2y-3xy^2+xy^2+y^3\\ =2x^3-x^2y-2xy^2+y^3\\ c,\left(x-2\right)\left(x^2-5x+1\right)-x\left(x^2+11\right)\\ =x^3-5x^2+x-2x^2+10x--x^3-11x\\ =x^3-7x^2\\ d,x\left(1-3x\right)\left(4-3x\right)-\left(x-4\right)\left(3x+5\right)\\ =x\left(4-15x+9x^2\right)-\left(3x^2-7x-20\right)\\ =4x-15x^2+9x^3-3x^2+7x+20\\ =9x^3-18x^2+11x+20\)