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15 tháng 10 2021

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

b: \(\dfrac{x^2-4xy+4y^2-4}{2x^2-4xy+4x}\)

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

\(=\dfrac{x-2y-2}{2x}\)

\(=\dfrac{\left(x+3\right)\left(x-1\right)}{\left(x+5\right)\left(x-2\right)}\cdot\dfrac{\left(x-2\right)\left(x-7\right)}{\left(x+3\right)\left(x-2\right)}:\dfrac{\left(x-1\right)\left(x-3\right)}{\left(x+2\right)\left(x+5\right)}\)

\(=\dfrac{\left(x-1\right)\left(x-7\right)}{\left(x+5\right)\left(x-2\right)}\cdot\dfrac{\left(x+2\right)\left(x+5\right)}{\left(x-1\right)\left(x-3\right)}=\dfrac{\left(x-7\right)\left(x+2\right)}{\left(x-2\right)\left(x-3\right)}\)

Bài 1:

\(D=-3x^2+x+15x-5-3\left(2x^2-5x+2\right)\)

\(=-3x^2+16x-5-6x^2+15x-6\)

\(=-9x^2+31x-11\)

\(=-9\cdot\dfrac{1}{9}+\dfrac{31}{3}-11\)

=-11-1+31/3=-12+31/3=-5/3

b: \(E=x^2+x-56-x^2+7x-10=8x-66\)

\(=-\dfrac{8}{5}-66=-\dfrac{338}{5}\)

c: \(F=-3\left(2x^2+x-16x-8\right)-\left(-3x^2+2x-15x+10\right)-4x^2+24x\)

\(=-6x^2+45x+24+3x^2+13x-10-4x^2+24x\)

\(=-4x^2+82x+14\)

\(=-4\cdot9-82\cdot3+14=-268\)

Bài 1: 

8: \(=\dfrac{x+3}{x\left(x-3\right)}\)

9: \(=\dfrac{x-2}{x-5}\cdot\dfrac{\left(x-5\right)\left(x+5\right)}{\left(x-2\right)^2}=\dfrac{x+5}{x-2}\)

10: \(=1:\dfrac{a-1}{a}=\dfrac{a}{a-1}\)

12: \(=\dfrac{6\left(x+1\right)}{3x\left(x+1\right)}=\dfrac{2}{x}\)

13: \(\dfrac{3}{x+3}-\dfrac{x-6}{x\left(x+3\right)}\)

\(=\dfrac{3x-x+6}{x\left(x+3\right)}=\dfrac{2x+6}{x\left(x+3\right)}=\dfrac{2}{x}\)

18 tháng 7 2021

Em bấm vào biểu tượng \(\sum\) trên thanh công cụ và gõ phân số để mn dễ hỗ trợ nhé!

18 tháng 7 2021

`(x^2+x-6)/(x^2+4x+3):(x^2-10x+25)/(x^2-4x-5)(x ne -1,x ne 5,x ne -3)`

`=((x-2)(x+3))/((x+1)(x+3)):(x-5)^2/((x+1)(x-5))`

`=(x-2)/(x+1):(x-5)/(x+1)`

`=(x-2)/(x-5)`

21 tháng 10 2016

\(\frac{2+x}{2-x}\div\frac{4x^2}{4-4x+x^2}\times\left(\frac{2}{2-x}-\frac{8}{8+x^3}\times\frac{4-2x+x^2}{2-x}\right)\)

\(=\frac{2+x}{2-x}\times\frac{4-4x+x^2}{4x^2}\times\left(\frac{2}{2-x}-\frac{8}{\left(2+x\right)\left(4-2x+x^2\right)}\times\frac{4-2x+x^2}{2-x}\right)\)

\(=\frac{2+x}{2-x}\times\frac{\left(2-x\right)^2}{4x^2}\times\left(\frac{2\left(2+x\right)}{\left(2+x\right)\left(2+x\right)}-\frac{8}{\left(2+x\right)\left(2-x\right)}\right)\)

\(=\frac{\left(2+x\right)\left(2-x\right)}{4x^2}\times\frac{4+2x-8}{\left(2+x\right)\left(2-x\right)}\)

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

\(=\frac{x-2}{2x^2}\)

 

 

30 tháng 10 2021

a. \(\dfrac{\left(x-2\right)^2}{2x\left(x-2\right)}=\dfrac{x-2}{2x}\)

b. \(\dfrac{\dfrac{1}{2}-2}{2.\dfrac{1}{2}}=-1,5\)