\(\frac{x^8-1}{\left(x^4+1\right)\left(x^2-1\right)}\)

\(=\frac{\left(x^2-1\right)\left(x^4+x^2+1\right)}{\left(x^4+1\right)\left(x^2-1\right)}\)

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

\(\frac{x^2+y^2-4+2xy}{x^2-y^2+4+4x}\)

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

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

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

\(\frac{4x^2+12x+9}{2x^2-x-6}\)

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

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

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

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

\(\frac{25-10x+x^2}{xy-5y}\)

\(=\frac{\left(5-x\right)^2}{-y\left(5-x\right)}\)

\(=-\frac{5-x}{y}\)

\(\frac{\left|x\right|-3}{x^2-9}\)

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

\(=\frac{1}{x+3}\)

\(\frac{3\left|x-4\right|}{3x^2-3x-36}\)

\(=\frac{3\left(x-4\right)}{3\left(x^2-x-12\right)}\)

\(=\frac{x-4}{x^2-4x+3x-12}\)

\(=\frac{x-4}{x\left(x-4\right)+3\left(x-4\right)}\)

\(=\frac{x-4}{\left(x-4\right)\left(x+3\right)}\)

\(=\frac{1}{x+3}\)

Bài này dễ sáng làmcho

a) ta có : \(D=R\backslash\left\{0\right\}\) \(\Rightarrow x\in D\) thì \(-x\in D\)

ta có : \(f\left(-x\right)=\dfrac{\left(-x\right)^4+3}{\left|-x\right|+4\left(-x\right)^2}=\dfrac{x^4+3}{\left|x\right|+4x^2}=f\left(x\right)\)

\(\Rightarrow\) hàm số này là hàm chẳn.

b) ta có : \(D=R\backslash\left\{\pm1\right\}\) \(\Rightarrow x\in D\) thì \(-x\in D\)

ta có : \(f\left(-x\right)=\dfrac{3\left(-x\right)^4-\left(-x\right)^2+5}{\left|-x\right|^5-1}=\dfrac{3x^4-x^2+5}{\left|x\right|^5-1}=f\left(x\right)\)

\(\Rightarrow\) hàm số này là hàm chẳn .

c) ta có : \(D=\left(-\infty;-3\right)\cup\left(3;+\infty\right)\) \(\Rightarrow x\in D\) thì \(-x\in D\)

ta có : \(f\left(-x\right)=\dfrac{1}{\sqrt{\left(-x\right)^2-9}}=\dfrac{1}{\sqrt{x^2-9}}=f\left(x\right)\)

\(\Rightarrow\) hàm số này là hàm chẳn.

d) ta có : \(D=R\) \(\Rightarrow x\in D\) thì \(-x\in D\)

ta có : \(f\left(-x\right)=\dfrac{-x}{\left|-5x+2\right|+\left|-5x-2\right|}=\dfrac{-x}{\left|5x-2\right|+\left|5x+2\right|}=-f\left(x\right)\)

\(\Rightarrow\) hàm số này là hàm lẽ .

a: \(f\left(x\right)=\left|x+2\right|-\left|x-2\right|\)

\(f\left(-x\right)=\left|-x+2\right|-\left|-x-2\right|=\left|x-2\right|-\left|x+2\right|=-f\left(x\right)\)

=>f(x) là hàm số lẻ

b: \(f\left(x\right)=\dfrac{3x^2}{2-\left|x\right|}\)

\(f\left(-x\right)=\dfrac{3\cdot\left(-x\right)^2}{2-\left|-x\right|}=\dfrac{3\cdot x^2}{2-\left|x\right|}=f\left(x\right)\)

=>f(x) là hàm số chẵn

2Fe3O4 + 10H2SO4 → 3Fe2(SO4)3 + SO2 + 10H2O

2FeCO3 + 4H2SO4 → Fe2(SO4)3 + SO2 + 2CO2 + 4H2O

1)(Fe2left(SO4 ight)3+6NaOH ightarrow2Feleft(OH ight)3downarrow+3Na2SO4)

(Fe2left(SO4 ight)3+6NaCl ightarrow2FeCl3+3Na2So4)

2 ) (Cu+2Hcl ightarrow CuCl2+H2uparrow)

(Cu+H2So4 ightarrow C ext{uS}O4+H2uparrow)

Phản ứng 1:

Phản ứng 2:

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Phản ứng 5: