Bài 1:

\(a,=6x^2+6x\\ b,=15x^3-10x^2+5x\\ c,=6x^3+12x^2\\ d,=15x^4+20x^3-5x^2\\ e,=2x^2+3x-2x-3=2x^2+x-3\\ f,=3x^2-5x+6x-10=3x^2+x-10\)

Bài 2:

\(a,\Leftrightarrow3x^2+3x-3x^2=6\\ \Leftrightarrow3x=6\Leftrightarrow x=2\\ b,\Leftrightarrow6x^2+3x-6x^2+9x-2x-3=10\\ \Leftrightarrow10x=13\Leftrightarrow x=\dfrac{13}{10}\)

a: =1/2x^3*x^2-1/2x^3*6x-1/2x^3*10

=1/2x^5-3x^4-5x^3

b: =-3x^2*5x^3+3x^2*4x^2-3x^2*3x+3x^2*3x

=-15x^5+12x^4-9x^3+9x^2

c: \(=3x\cdot5x^2-3x\cdot2x-3x=15x^3-6x^2-3x\)

d: \(=\dfrac{1}{2}x^2y\cdot2x^3-\dfrac{1}{2}x^2y\cdot\dfrac{2}{5}xy^2-\dfrac{1}{2}x^2y=x^5y-\dfrac{1}{5}x^3y^3-\dfrac{1}{2}x^2y\)

Tham khảo

a)

-7x²(3x - 4y)

= -7x².3x + 7x^2ư.4y

= -21x² + 28x²y

b)

(x - 3)(5x - 4)

= x.5x - x.4 - 3.5x + 3.4

= 5x² - 4x - 15x + 12

= 5x² - 19x + 12

c)

(2x - 1)² = 4x² - 4x + 1

d)

(x + 3)(x - 3) = x² - 3² = x² - 9

a, = -21x³ +28x²y

b, = 5x² -4x -15x +12

= 5x² -19x +12

c, =x² -9

\(a,=-21x^3+28x^2y\\ b,=5x^2-4x-15x+12=5x^2-19x+12\\ c,=4x^2-4x+1\\ d,=49-x^2\)

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

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

a: \(-2x\left(3x+4\right)+\left(2x+5\right)\left(9-7x\right)\)

\(=-6x^2-8x+18x-14x^2+45-35x\)

\(=-20x^2-25x+45\)

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

\(=x^2-10x+25-\left(16-x^2\right)\)

\(=x^2-10x+25-16+x^2=2x^2-10x+9\)

c: \(\left(4x^2-12x+8\right):\left(x-2\right)\)

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

\(=\frac{4\left(x-2\right)\left(x-1\right)}{x-2}=4\left(x-1\right)=4x-4\)

a: \(=\dfrac{2\left(x+2\right)\left(x-1\right)}{x+2}=2x-2\)

b: \(=\dfrac{2x^3+x^2-6x^2-3x+2x+1}{2x+1}=x^2-3x+1\)

c: \(=\dfrac{x^3+2x^2-2x^2-4x+2x+4}{x+2}=x^2-2x+2\)

d: \(=\dfrac{x^2\left(x-3\right)}{x-3}=x^2\)

`@` `\text {Ans}`

`\downarrow`

a: \(\left(19x^2-14x^3+9-20x+2x^4\right):\left(1+x^2-4x\right)\)

\(=\left(2x^4-14x^3+19x^2-20x+9\right):\left(x^2-4x+1\right)\)

\(=\left(2x^4-8x^3+2x^2-6x^3+24x^2-6x-7x^2+28x-7-42x+16\right)\) :\(\left(x^2-4x+1\right)\)

\(=2x^2-6x-7+\frac{-42x+16}{x^2-4x+1}\)

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

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

\(=3x^2-2x+4+\frac{16}{x^2-2}\)

c: \(\left(2x^3-26x-24\right):\left(x^2+4x+3\right)\)

\(=\left(2x^3+8x^2+6x-8x^2-32x-24\right):\left(x^2+4x+3\right)\)

=2x-8