\(a,\left(3x+1\right)\left(3x-1\right)-\left(18x^3+5x^2-2x\right):2x\\ =\left(9x^2-1\right)-\left(9x^2+\dfrac{5}{2}x-1\right)\\ =9x^2-1-9x^2-\dfrac{5}{2}x+1=\dfrac{5}{2}x\)

\(b,3x\left(x-2021\right)-x+2021=0\\ \Rightarrow b,3x\left(x-2021\right)-\left(x-2021\right)=0\\ \Rightarrow\left(x-2021\right)\left(3x-1\right)=0\\ \Rightarrow\left[{}\begin{matrix}x=2021\\x=\dfrac{1}{3}\end{matrix}\right.\)

a. \(3x\left(2x+1\right)=6x^2+3x\)

b. \(\left(12x^3-18x^2+6x\right):6x=2x^2-3x+1\)

c. \(\dfrac{7x+6}{5x-1}+\dfrac{8x-9}{5x-1}=\dfrac{15x-3}{5x-1}=\dfrac{3\left(5x-1\right)}{5x-1}=3\)

\(a.3x\left(2x+1\right)\\ =6x^2+3x\)

\(b.\left(12x^3-18x^2+6x\right):6x\\ =2x^2-3x+1\)

\(c.\dfrac{7x+6}{5x-1}+\dfrac{8x-9}{5x-1}=\dfrac{7x+6+8x-9}{5x-1}=\dfrac{15x-3}{5x-1}=\dfrac{3\left(5x-1\right)}{5x-1}=3\)

a. 

b. 

c. \(\dfrac{7x+6}{5x-1}+\dfrac{8x-9}{5x-1}=\dfrac{15x-3}{5x-1}=\dfrac{3\left(5x-1\right)}{5x-1}=3\)

a)2x(x²-3y)

=2x³-6xy

-18x³y⁴:3xy⁴

=(-18:3) (x³:x) (y⁴:y⁴)

=-6x²

a) \(2x^2\left(3x-5\right)=2x^2.3x-2x^2.5=6x^3-10x^2\)

b) \(\left(12x^3y+18x^2y\right):2xy\)\(=12x^3y:2xy+18x^2y:2xy\)

                                                        \(=6x^2+9x=3x\left(2x+3\right)\)

bạn MMS_Hồ Khánh Châu trả lời đúng rùi đó

Bài làm 

a, \(2x^2\left(3x-5\right)=6x^3-10x^2\)

b, \(\left(12x^3y^2-18x^2y\right):2xy=\left(12x^3y^2:2xy\right)-\left(18x^2y:2xy\right)=6x^2y-9x\)

\(2x\left(x^2-3y\right)=2x^3-6xy\)

\(-18x^3y^4:3xy^4=-\left(6x^2\right)\)

a) \(2x\left(x^2-3y\right)\)

\(=2x^3-6xy\)

b) \(-18x^3y^4:3xy^4\)

\(=-6x^2\)

a) (x - 3)(2x + 5)

= 2x² + 5x - 6x - 15

= 2x² - x - 15

b) (x²y³ + 18x²y² - 3xy²) : 9xy²

= 9xy + 2x - \(\frac{1}{3}\)

Trần Tuyết Tâm

\(a,5xyz-12x^2yz^2-17xy^3-21x^2yz^2-6xyz+M=0\)

\(\Rightarrow-xyz-33x^2yz^2-17xy^3+M=0\)

\(\Rightarrow M=xyz+33x^2yz^2+17xy^3\)

Vậy...

b, \(M-\left(6x^4y^3-7xyz^3+9xyz\right)=4x^4y^3-3xyz^3-5xyz\)

\(\Rightarrow M=4x^4y^3-3xyz^3-5xyz+6x^4y^3-7xyz^3+9xyz\)

\(\Rightarrow M=10x^4y^3-10xyz^3+4xyz\)

Vậy...

a) Ta có:

\(M=-xyz+12x^2yz^2+17xy^3+21x^2yz^2+6xyz\)

\(=xyz+33x^2yz^2+17xy^3\)

b) \(M=4x^4y^3-3xyz^3-5xyz+\left(6x^4y^3-7xyz^3+9xyz\right)\)

\(=4x^4y^3+6x^4y^3-3xyz^3-7xyz^3-5xyz+9xyz\)

\(=10x^4y^3-10xyz^3+4xyz\)

a, \(5xyz-12x^2yz^2-17xy^3-21x^2yz^2-6xyz+M=0\)

\(\Rightarrow M=-5xyz+12x^2yz^2+17xy^3+21x^2yz^2+6xyz\)

\(\Rightarrow M=\left(-5xyz+6xyz\right)+\left(12x^2yz^2+21x^2yz^2\right)+17xy^3\)

\(\Rightarrow M=xyz+33x^2yz^2+17xy^3\)

b, \(M-\left(6x^4y^3-7xyz^3+9xyz\right)=4x^4y^3-3xyz^3-5xyz\)

\(\Rightarrow M=4x^4y^3-3xyz^3-5xyz+\left(6x^4y^3-7xyz^3+9xyz\right)\)

\(\Rightarrow M=4x^4y^3-3xyz^3-5xyz+6x^4y^3-7xyz^3+9xyz\)

\(\Rightarrow M=\left(4x^4y^3+6x^4y^3\right)+\left(-3xyz^3-7xyz^3\right)+\left(-5xyz+9xyz\right)\)

\(\Rightarrow M=10x^4y^3-10xyz^3+4xyz\)

Chúc bạn học tốt!!!

a) (-5x³ + 15x² + 18x) : (-5x)

= (-5x³) : (-5x) + 15x² : (-5x) + 18x : (-5x)

= [(-5): (-5)] . (x³ : x) + [15 : (-5)] . (x² : x) + [18 : (-5)]. (x : x)

=  x² – 3x - \(\dfrac{{18}}{5}\)

b) (-2x⁵ – 4x³ + 3x²) : 2x²

= (-2x⁵ : 2x²) + (-4x³ : 2x²) + (3x² : 2x²)

= [(-2) : 2] . (x⁵ : x²) + [(-4) : 2] . (x³ : x²) + (3 : 2) . (x² : x²)

= -x³ – 2x + \(\dfrac{3}{2}\)