\(-3x(x+2)^2+(x+3)(x-1)(x+1)-(2x-3)^2\)

 

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30 tháng 7 2018

= x3 + 9x+ 81x + 27  - x3 - 64

= 9x2 + 81x - 34

28 tháng 7 2019

Bài Làm:

\(1,\left(2x-1\right)^2-3\left(2x-1\right)^2=0\)

\(\Leftrightarrow-2\left(2x-1\right)^2=0\)

\(\Leftrightarrow\left(2x-1\right)^2=0\)

\(\Leftrightarrow2x-1=0\)

\(\Leftrightarrow x=\frac{1}{2}\)

Vậy ...

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

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

\(\Leftrightarrow\left(x+1\right)\left[\left(x-1\right)^2-1\right]=0\)

\(\Leftrightarrow\left(x+1\right)\left[x^2-2x+1-1\right]=0\)

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

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

\(\Leftrightarrow\left[{}\begin{matrix}x=0\\x+1=0\\x-2=0\end{matrix}\right.\) \(\Leftrightarrow\left[{}\begin{matrix}x=0\\x=-1\\x=2\end{matrix}\right.\)

Vậy ...

\(3,x^4-3x^2=x^2\)

\(\Leftrightarrow x^4-3x^2-x^2=0\)

\(\Leftrightarrow x^4-4x^2=0\)

\(\Leftrightarrow x^2\left(x^2-4\right)=0\)

\(\Leftrightarrow x^2\left(x-2\right)\left(x+2\right)=0\)

\(\Leftrightarrow\left[{}\begin{matrix}x^2=0\\x-2=0\\x+2=0\end{matrix}\right.\Leftrightarrow\left[{}\begin{matrix}x=0\\x=2\\x=-2\end{matrix}\right.\)

Vậy ...

Chúc pạn hok tốt!!!

28 tháng 7 2019

1/ \(\left(2x-1\right)^2-3\left(2x-1\right)^2=0\)

\(\left(2x-1\right)^2\left(1-3\right)=0\)

\(\left(2x-1\right)^2\cdot\left(-2\right)=0\)

\(\Rightarrow\text{ }\left(2x-1\right)^2=0\)

\(2x-1=0\)

\(2x=0+1=1\)

\(x=\frac{1}{2}\)

28 tháng 7 2019

1) \(\left(2x-1\right)^2-3\left(2x-1\right)^2=0\)

=> \(\left(2x-1\right)^2\left(1-3\right)=0\)

=> \(\left(2x-1\right)^2.\left(-2\right)=0\)

=> \(\left(2x-1\right)^2=0\)

=> \(2x-1=0\)

=> \(2x=1\)

=> \(x=1:2=\frac{1}{2}\)

29 tháng 11 2019

Làm ngắn gọn thôi nhé :v

\(A=\frac{2x}{x^2-3x}+\frac{2x}{x^2-4x+3}+\frac{x}{x-1}\)

\(A=\frac{x^5-3x^4-3x^3+11x^2-6x}{x^5-8x^2+22x^2-24x+9}\)

\(A=\frac{x^4-3x^3-3x^2+11x-6}{x^4-8x^3+22x^2-24x+9}\)

\(A=\frac{\left(x-1\right)\left(x-1\right)\left(x+2\right)\left(x-3\right)}{\left(x-1\right)\left(x-1\right)\left(x-3\right)\left(x-3\right)}\)

\(A=\frac{x+2}{x-3}\)

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

\(B=\frac{-x^4-4x^3+16x+16}{-x^4+8x^2-16}\)

\(B=\frac{\left(-x-2\right)\left(x+2\right)\left(x+2\right)\left(x-2\right)}{\left(-x-2\right)\left(x-2\right)\left(x+2\right)\left(x-2\right)}\)

\(B=\frac{x+2}{x-2}\)

\(C=\frac{1+x}{3-x}-\frac{1-2x}{3+x}-\frac{x\left(1-x\right)}{9-x^2}\)

\(C=\frac{1+x}{3-x}-\left(\frac{1-2x}{3+x}\right)-\frac{x\left(1-x\right)}{9-x^2}\)

\(C=\frac{10x}{-x^2+9}\)

\(D=\frac{5}{2x^2+6x}-\frac{4-3x^2}{x^2-9}-3\)

\(D=\frac{5}{2x^2+6x}-\left(\frac{4-3x^2}{x^2-9}\right)-3\)

\(D=\frac{51x^2+138x-45}{2x^4+6x^2-18x^2-54x}\)

\(D=\frac{3\left(17x-5\right)\left(x+3\right)}{2x\left(x+3\right)\left(x+3\right)\left(x-2\right)}\)

\(D=\frac{51x-15}{2x^3-18x}\)

\(E=\frac{3x+2}{x^2-2x+1}-\frac{6}{x^2-1}-\frac{3x-2}{x^2+2x+1}\)

\(E=\frac{3x+2}{x^2-2x+1}-\frac{6}{x^2-1}-\left(\frac{3x-2}{x^2+2x+1}\right)\)

\(E=\frac{10x^4-10}{x^6-3x^4+3x^2-1}\)

\(E=\frac{10\left(x^2+1\right)\left(x+1\right)\left(x-1\right)}{\left(x+1\right)\left(x+1\right)\left(x+1\right)\left(x-1\right)\left(x-1\right)\left(x-1\right)}\)

\(E=\frac{10x^2+10}{x^4-2x+1}\)

28 tháng 10 2020

( x + 2 )( x2 - 2x + 4 ) - 2( x + 1 )( 1 - x )

= x3 + 8 + 2( x + 1 )( x - 1 )

= x3 + 8 + 2( x2 - 1 )

= x3 + 8 + 2x2 - 2

= x3 + 2x2 + 6 

1 tháng 7 2017

@Nguyễn Quang Trung

1 tháng 7 2017

Ta có : \(\frac{x}{x-3}-\frac{x^2+3x}{2x+3}\left(\frac{x+3}{x^2-3x}-\frac{x}{x^2-9}\right)\)

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

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

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

\(=\frac{x}{x-3}-\frac{x^2+3x}{2x+3}\left(\frac{x^2+6x+9-x^2}{x\left(x^2-3\right)}\right)\)

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

\(=\frac{x}{x-3}-\frac{3x^2+9x}{x\left(x^2-3\right)}\)(mk sợ mk làm sai lắm nếu làm sai thì sory nhá)