a: \(=2x^{2n+1-2n}-2\cdot x^{2n}\cdot3\cdot x^{2-2n}+3\cdot x^{2n-1+1-2n}-9\cdot x^{2n-1+2-2n}\)

\(=2x-6x^2+3-9x\)

\(=-6x^2-7x+3\)

b: \(=\left(5x\right)^3-\left(2y\right)^3=125x^3-8y^3\)

a: \(=24x^{2m-1+3-2m}y^{6-3m}-\dfrac{24}{7}y^{3n-7+6-3n}\cdot x^{3-2m}+8x^{3-2m+2m}\cdot y^{6-3n+3m}-24x^{3-2m}y^{6-2n+2}\)

\(=24x^2y^{6-3m}-\dfrac{24}{7}x^{3-2m}\cdot y^{-1}+8x^3y^{-3n+3m+6}-24x^{3-2m}y^{-2n+8}\)

b: \(=2x^{2n+1-2n}-6x^{2n+2-2n}+3x^{2n-1+1-2n}-9x^{2n-1+2-2n}\)

\(=2x-6x^2+3-9x\)

\(=-6x^2-7x+3\)

Đề bị lỗi công thức rồi bạn. Bạn cần viết lại để được hỗ trợ tốt hơn.

a) 1/3x + 2/5x - 2/5 = 0

=> x = 0,54

b) 12n - 4n^2 - 18 + 6n +0

<=> -4n^2 + 6n - 18 = 0

<=> (-4n)^2 + 6n + 12n - 18 +0

<=> - 2n (2n-3 ) + 6 ( 2n - 3 ) = 0

,<=> ( 6 - 2n ) ( 2n -3 )=0

<=> 6 - 2n = 0 => n +3 / 2n-3 =0 => n = 3/2

Ý c là thực hiện phép tính nha mọi người

a/ \(\left(2n^3-5n^2+1\right):\left(2n-1\right)=n^2-2n-1\)

b/ \(x\ne0;\pm2\)

\(\left(\frac{x^2}{x\left(x^2-4\right)}-\frac{6}{3\left(x-2\right)}+\frac{1}{x+2}\right):\left(\frac{x^2-4+10-x^2}{x+2}\right)\)

\(=\left(\frac{x}{x^2-4}-\frac{2\left(x+2\right)}{x^2-4}+\frac{x-2}{x^2-4}\right):\left(\frac{6}{x+2}\right)\)

\(=\left(\frac{x-2x-4+x-2}{\left(x-2\right)\left(x+2\right)}\right).\left(\frac{x+2}{6}\right)\)

\(=\frac{-6}{\left(x-2\right)\left(x+2\right)}.\frac{\left(x+2\right)}{6}=-\frac{1}{x-2}=\frac{1}{2-x}\)

c/

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

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

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

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

\(\Rightarrow\left(x+3\right)=\left(2x-3\right)\)

\(\Rightarrow x+3=2x-3\)

\(\Rightarrow x+3-2x+3=0\)

\(\Rightarrow-x+6=0\)

\(\Rightarrow x=6\)

Vậy x=6

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

\(\Rightarrow x+3=2x-3\)

\(x+3-2x+3=0\)

\(\left(x-2x\right)+\left(3+3\right)=0\)

\(-x+6=0\)

\(-x=0-6\)

\(-x=-6\)

\(\Rightarrow x=6\)

Vậy \(x=6\).