a) –4x(5x^2 – 2xy + y^2)

= -20x^3 + 8x^2y - 4xy^2

b) (4x – 1)(2x^2 – x – 1)

= 8x^3 - 4x^2 - 4x - 2x^2 + x + 1

= 8x^3 - 6x^2 - 3x + 1

A=(12x³y⁴-15x²y³-9x³y²):3x²y

  =(12x³y⁴:3x²y)-(15x²y³:3x²y)- (9x³y²:3x²y)

  =4x²y³-5y²-3x²

B, sai đề bạn ơi

a: Ta có: \(\left(2x+3\right)^2+\left(2x-3\right)^2-2\left(4x^2-9\right)\)

\(=4x^2+12x+9+4x^2-12x+9-8x^2+18\)

\(=36\)

Bài 2: 

a: \(\left(y^2+6x^2\right)\left(y^2-6x^2\right)=y^4-36x^4\)

b: \(\left(4x+5\right)\left(16x^2-20x+25\right)=\left(16x^2-25\right)\left(4x-5\right)\)

\(=64x^3-16x^2-100x+125\)

\(Bài1:\\ a,\left(4x-1\right)\left(2x^2-x-1\right)=4x\left(2x^2-x-1\right)-\left(2x^2-x-1\right)=8x^3-4x^2-4x-2x^2+x+1=8x^3-6x^2-3x+1\\ b,\left(4x^3+8x^2-2x\right):2x\\ =2x\left(2x^2+4x-1\right):2x\\ =2x^2+4x-1\)

\(Bài2:\\ a,2x^3-8x^2+8x=2x\left(x^2-4x+4\right)=2x\left(x-2\right)^2\\ b,2xy+2x+yz+z=2x\left(y+1\right)+z\left(y+1\right)=\left(y+1\right)\left(2x+z\right)\\ c,x^2+2x+1-y^2=\left(x+1\right)^2-y^2=\left(x-y+1\right)\left(x+y+1\right)\)

Bài 2: 

a: \(\Leftrightarrow\left(x-2\right)\left(x+1\right)=0\)

\(\Leftrightarrow\left[{}\begin{matrix}x=2\\x=-1\end{matrix}\right.\)

Cần gấp

`@` `\text {Ans}`

`\downarrow`

`a)`

\(2x(4x²+x-3)\)

`= 2x*4x^2 + 2x*x + 2x*(-3)`

`= 8x^3 + 2x^2 - 6x`

`b)`

\([(-9x)+4x]: (-3x)-3x²\)

`= (-9x) \div (-3x) + 4x \div (-3x) - 3x^2`

`= 3 - 4/3 - 3x^2`

`= 5/3 - 3x^2`

a) \(2x\left(4x^2+x-3\right)\)

\(=2x\cdot4x^2+2x\cdot x+2x\cdot\left(-3\right)\)

\(=8x^3+2x^2-6x\)

b) \(\left[\left(-9x\right)+4x\right]:\left(-3x\right)-3x^2\)

\(=-5x:\left(-3x\right)-3x^2\)

\(=-3x^2+\dfrac{5}{3}\)

Giúp với mọi người

c: \(=3x^3-4x^2+6x^2-8x=3x^2+2x^2-8x\)