a ) \(\left(3x^2-4x+5\right)\left(2x^2-4\right)-2x\left(3x^3-4x^2+8\right)\)

\(=\left(3x^2-4x+5\right).2x^2-4\left(3x^2-4x+5\right)-6x^4+8x^3-16x\)

\(=6x^4-8x^3+10x^2-12x^2+16x-20-6x^4+8x^3-16x\)

\(=\left(6x^4-6x^4\right)+\left(8x^3-8x^3\right)-\left(12x^2-10x^2\right)+\left(16x-16x\right)-20\)

\(=-2x^2-20\)

b ) \(\left(1-3x+x^2\right)\left(2-4x\right)+2x\left(2x^2+5\right)\)

\(=2\left(1-3x+x^2\right)-4x\left(1-3x+x^2\right)+4x^3+10x\)

\(=2-6x+2x^2-4x+12x^2-4x^3+4x^3+10x\)

\(=\left(4x^3-4x^3\right)+\left(12x^2+2x^2\right)+\left(10x-6x-4x\right)+2\)

\(=14x^2+2\)

`K(x)=F(x)+G(x)`

`K(x)=(3x^2+2x-5)+(-3x^2-2x+2)`

`= 3x^2+2x-5-3x^2-2x+2`

`= (3x^2-3x^2)+(2x-2x)+(-5+2)`

`= -3`

Bậc của đa thức: `0`

`@` `\text {dnammv}`

Giúp mk câu hỏi này vs

\(2x\left(3x^2-7x+2\right)\)

\(=6x^3-14x^2+4x\)

\(\left(x-2\right)\left(3x^2+2x+4\right)\)

\(=3x^3+\left(-4x^2\right)+\left(-8\right)\)

\(\left(3x^2y^2+6x^2y^3-12xy\right)\div3xy\)

\(=xy+2xy-4\)

x^2/x-2+4-4x/x-2 ???

1) 2x(3x^2-7x+2)

<=> \(6x^3-14x^2+4x\)

2) (x-2)(3x^2+2x+4)

<=> \(3x^3-4x^2-8\)

3) (3x^2y^2+6x^2y^3-12xy)÷3xy

<=> xy + 2xy² -4 

4) X^2/x-2+4-4x/x-2

<=> \(\dfrac{x^2-4x+4}{x-2}=\dfrac{\left(x-2\right)^2}{x-2}=x-2\)

a) x^2 - 11x + 18 = 0 

=> x^2 - 2x - 9x + 18 = 0 

=> x ( x- 2 ) - 9 ( x- 2 ) = 0 

=> ( x- 9 )( x- 2 )= 0 

=> x- 9 = 0 hoặc x - 2 = 0 

=> x= 9 hoặc x = 2 

\(\dfrac{x^3+2x^2-2x-1}{x^2+3x+1}\)

\(=\dfrac{\left(x^3+3x^2+x\right)-\left(x^2+3x+1\right)}{x^2+3x+1}\)

\(=\dfrac{\left(x-1\right)\left(x^2+3x+1\right)}{x^2+3x+1}=x-1\)

`@` `\text {Ans}`

`\downarrow`

`a)`

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

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

`= 3x^4 - 9x^2 + 2x^3 - 6x + 12x + 8 - 3x^4 - 2x^3`

`= (3x^4 - 3x^4) + (2x^3 - 2x^3) - 9x^2 + (-6x+12x) + 8`

`= -9x^2 + 6x + 8`