a) \(\dfrac{5x}{10}=\dfrac{x}{2}\)

b) \(\dfrac{4xy}{2y}=2x\left(y\ne0\right)\)

c) \(\dfrac{5x-5y}{3x-3y}=\dfrac{5}{3}\left(x\ne y\right)\)

d) \(\dfrac{x^2-y^2}{x+y}=x-y\left(đk:x\ne-y\right)\)

e) \(\dfrac{x^3-x^2+x-1}{x^2-1}=\dfrac{x^2+1}{x+1}\left(đk:x\ne\pm1\right)\)

f) \(\dfrac{x^2+4x+4}{2x+4}=\dfrac{x+2}{2}\left(đk:x\ne-2\right)\)

a: ĐKXĐ: \(3x^2+6x\ne0\)

=>\(x^2+2x\ne0\)

=>\(x\cdot\left(x+2\right)\ne0\)

=>\(x\notin\left\{0;-2\right\}\)

b: ĐKXĐ: \(x^3+64\ne0\)

=>\(x^3\ne-64\)

=>\(x\ne-4\)

c: ĐKXĐ: \(x^2-1\ne0\)

=>\(x^2\ne1\)

=>\(x\notin\left\{1;-1\right\}\)

a) ĐKXĐ: 

\(x^2-1\ne0\Leftrightarrow x\ne\pm1\)

b) \(A=\dfrac{x^2-2x+1}{x^2-1}\)

\(A=\dfrac{x^2-2\cdot x\cdot1+1^2}{x^2-1^2}\)

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

\(A=\dfrac{x-1}{x+1}\)

c) Thay x = 3 vào A ta có:

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

a) ĐKXĐ: 

\(9x^2-y^2\ne0\Leftrightarrow\left(3x\right)^2-y^2\ne0\Leftrightarrow\left(3x-y\right)\left(3x+y\right)\ne0\)

\(\Leftrightarrow3x\ne\pm y\) 

b) \(B=\dfrac{6x-2y}{9x^2-y^2}\)

\(B=\dfrac{2\cdot3x-2y}{\left(3x\right)^2-y^2}\)

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

\(B=\dfrac{2}{3x+y}\)

Thay x = 1 và \(y=\dfrac{1}{2}\) và B ta có:

\(B=\dfrac{2}{3\cdot1+\dfrac{1}{2}}=\dfrac{2}{3+\dfrac{1}{2}}=\dfrac{2}{\dfrac{7}{2}}=\dfrac{4}{7}\)

\(a,ĐK:x\ne0;x\ne1;x\ne\pm2\\ b,A=\left[\dfrac{2+x}{2-x}-\dfrac{2-x}{2+x}+\dfrac{4x^2}{\left(2-x\right)\left(x+2\right)}\right]\cdot\dfrac{x\left(2-x\right)}{x-1}\\ A=\dfrac{x^2+4x+4-x^2+4x-4+4x^2}{\left(2-x\right)\left(x+2\right)}\cdot\dfrac{x\left(2-x\right)}{x-1}\\ A=\dfrac{4x\left(x+1\right)\cdot x}{\left(x+2\right)\left(x-1\right)}=\dfrac{4x^2}{x+2}\)

ĐKXĐ: \(x\ne-3\)

Tại \(x=2\Rightarrow A=\dfrac{2^2+3}{3.2+9}=\dfrac{7}{15}\)

a) A xác định khi \(3x+9\ne0\Leftrightarrow x\ne-3\).

b) Với \(x=2\) thì \(A=\dfrac{2^2+3}{3\cdot2+9}=\dfrac{7}{15}\).

ĐKXĐ: \(x\ne0;y\ne0\)

\(ĐK:x\ne2y;x\ne0;y\ne0\)

câu a trc nhé

câu b nek (bn thông cảm nha,mk gõ trên mathtype nên gõ văn bản hơi khó)

`a, x ne 6`

`b, x ne -3y`

`c, x in RR`.

a) ĐK: \(x\ne6\)

b) ĐK: \(x\ne-3\)