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

Câu 1 : 

a.

1. 2Mg + O₂ ---t^o---> 2MgO

2. 2MgO + HCl -> MgCl₂ + H₂O

3. MgCl₂ + Na₂CO₃ ---t^o--> MgCO₃ + 2NaCl 

4.MgCO₃ + H₂SO₄ ---t^o---> MgSO₄ + H₂O + CO₂

5. MgSO₄ + 2HNO₃ ---t^o--> Mg(NO₃)₂ + H₂SO₄

6. Mg(NO₃)₂ + 2H₂O -> Mg(OH)₂ + 2HNO₃

7. Mg(OH)₂ ---t^o---> MgO + H₂O

8. MgCl₂ + H₂O -> Mg(OH)₂ + HCl

9. MgCO₃ + 2HNO₃ ----t^o---> Mg(NO₃)₂ + H₂O + CO₂

umk để sửa lại 

\(-6x^2.\left(x^2y+xy^2+xy^3\right)\\ =-6x^4y-6x^3y^2-6x^3y^3\)

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

\(-\dfrac{1}{4}.13\dfrac{9}{11}-0,25.6\dfrac{2}{11}\\ =-\dfrac{1}{4}.13\dfrac{9}{11}-\dfrac{1}{4}.6\dfrac{2}{11}\\ =-\dfrac{1}{4}.\left(13-6\right).\left(\dfrac{9}{11}-\dfrac{2}{11}\right)\\ =-\dfrac{1}{4}.7.\dfrac{7}{11}\\ =-\dfrac{49}{44}\)

\(6.\dfrac{1}{2}x:\left(x^2-8x+32\right)\\ =3x:\left(x^2-8x+32\right)\\ =3x-\dfrac{3}{8}+\dfrac{3}{32}\\ =3x-\dfrac{9}{32}\)

\(7x^2y.\left(5x^2+6x-3\right)\\ =35x^4y+42x^3y-21x^2y\)