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20 tháng 8 2018

a) b 3 + 3 b 2 + 2 b 3 + 1 .          b) 0.

22 tháng 7 2023

a) \(\dfrac{a-1}{a+1}+\dfrac{3-a}{a+1}\)

\(=\dfrac{a-1+3-a}{a+1}\)

\(=\dfrac{2}{a+1}\)

b) \(\dfrac{b}{a-b}+\dfrac{a}{b-a}\)

\(=\dfrac{b}{a-b}+\dfrac{-a}{a-b}\)

\(=\dfrac{b-a}{a-b}\)

\(=-1\)

c) \(\dfrac{\left(a+b\right)^2}{ab}-\dfrac{\left(a-b\right)^2}{ab}\)

\(=\dfrac{\left[\left(a+b\right)-\left(a-b\right)\right]\left[\left(a+b\right)+\left(a-b\right)\right]}{ab}\)

\(=\dfrac{4ab}{ab}\)

\(=4\)

22 tháng 7 2023

`a, (a-1)/(a+1) + (3-a)/(a+1)`

`= (a-1+3-a)/(a+1)`

`=2/(a+1)`

`b, b/(a-b) + a/(b-a)`

`=  b/(a-b) - a/(a-b)`

`= (b-a)/(a-b)`

`c, (a+b)^2/(ab) -(a-b)^2/(ab)`

`=(a^2+2ab+b^2-a^2+2ab-b^2)/(ab)`

`= (4ab)/(ab)`

`a, a/(a-3) - 3/(a+3) = (a(a+3) - 3(a-3))/(a^2-9)`

`= (a^2+9)/(a^2-9)`

`b, 1/(2x) + 2/x^2 = x/(2x^2) + 4/(2x^2) = (x+4)/(2x^2)`

`c, 4/(x^2-1) - 2/(x^2+x) = (4x)/(x(x-1)(x+1)) - (2(x-1))/(x(x+1)(x-1))`

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

`= 2/(x(x-1))`

Để A,B,C là phân số thì \(\left\{{}\begin{matrix}a-1< >0\\a-2< >0\end{matrix}\right.\Leftrightarrow a\in Z\backslash\left\{1;2\right\}\)

22 tháng 7 2023

a) \(\dfrac{3x^2y}{2xy^5}=\dfrac{3x}{2y^4}\)

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

c) \(\dfrac{ab^2-a^2b}{2a^2+a}=\dfrac{ab\left(b-a\right)}{a\left(2a+1\right)}=\dfrac{b\left(b-a\right)}{2a+1}=\dfrac{b^2-ab}{2a+1}\)

d) \(\dfrac{12\left(x^4-1\right)}{18\left(x^2-1\right)}=\dfrac{2\left(x^2-1\right)\left(x^2+1\right)}{3\left(x^2-1\right)}=\dfrac{2\left(x^2+1\right)}{3}\)

`a, (3x^2y)/(2xy^5)`

`= (3x)/(2y^4)`

`b, (3x^2-3x)/(x-1)`

`= (3x(x-1))/(x-1)`

`= 3x`

`c, (ab^2-a^2b)/(2a^2+a)`

`= (b(a-b))/((2a+1))`

`d, (12(x^4-1))/(18(x^2-1)) = (2(x^2+1))/3`.

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

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

\(=\dfrac{x^4+x^3-2x^2+2x^2+4x+x^2-1}{\left(x-1\right)\left(x+1\right).\left(x+2\right)}\)

\(=\dfrac{x^4+x^3+x^2+4x-1}{\left(x^2-1\right).\left(x+2\right)}\)

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

a: \(=\dfrac{3b+4a}{6ab}\)

b: \(=\dfrac{x^2-2x+1-x^2-2x-1}{x^2-1}=\dfrac{-4x}{x^2-1}\)

c: \(=\dfrac{xz+yz-xy-xz}{xyz}=\dfrac{yz-xy}{xyz}=\dfrac{z-x}{xz}\)

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

e: \(=\dfrac{x-2+2}{\left(x-2\right)^2}=\dfrac{x}{\left(x-2\right)^2}\)

11 tháng 11 2021

Bài 1: 

c: ĐKXĐ: \(x\notin\left\{-1;3\right\}\)

22 tháng 7 2023

a) \(\dfrac{3x^2+6xy}{6x^2}=\dfrac{3x\left(x+2y\right)}{6x^2}=\dfrac{x+2y}{2x}\)

b) \(\dfrac{2x^2-x^3}{x^2-4}=\dfrac{x^2\left(2-x\right)}{\left(x+2\right)\left(x-2\right)}=\dfrac{-x^2}{x+2}\)

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

`a, (3x^2+6xy)/(6x^2) = (x+2y)/(3x)`

`b, (2x^2-x^3)/(x^2-4) = (x^2(2-x))/((x-2)(x+2))`

`= -x^2/(x+2)`

`c, (x+1)/(x^3+1) = 1/(x^2-x+1)`

5 tháng 3 2022

mik cần rất rất gấp ạ

Bài 2: 

a: 1/3=20/60

1/5=12/60

1/12=5/60

b: 1/3=16/48

1/12=4/48

1/48=1/48

Bài 2: 

a: 1/3=20/60

1/5=12/60

1/12=5/60

b: 1/3=16/48

1/12=4/48

1/48=1/48

6 tháng 3 2022

Bài 2: 

a: 1/3=20/60

1/5=12/60

1/12=5/60

b: 1/3=16/48

1/12=4/48

1/48=1/48