tưởng cày nick kia?

ĐKXĐ:\(x\ne\pm1\)

\(\dfrac{2x}{x-1}-\dfrac{x}{x+1}=1\\ \Leftrightarrow\dfrac{2x\left(x+1\right)}{\left(x-1\right)\left(x+1\right)}-\dfrac{x\left(x-1\right)}{\left(x-1\right)\left(x+1\right)}1-\dfrac{\left(x-1\right)\left(x+1\right)}{\left(x-1\right)\left(x+1\right)}=0\\ \Leftrightarrow\dfrac{2x^2+2x-x^2+x-x^2+1}{\left(x-1\right)\left(x+1\right)}=0\\ \Rightarrow3x+1=0\\ \Leftrightarrow x=-\dfrac{1}{3}\left(tm\right)\)

\(M=\dfrac{3^2}{2.5}+\dfrac{3^2}{5.8}+...+\dfrac{3^2}{98.101}\\ =3\left(\dfrac{3}{2.5}+\dfrac{3}{5.8}+...+\dfrac{3}{98.101}\right)\\ =3\left(\dfrac{1}{2}-\dfrac{1}{5}+\dfrac{1}{5}-\dfrac{1}{8}+...+\dfrac{1}{98}-\dfrac{1}{101}\right)\\ =3.\left(\dfrac{1}{2}-\dfrac{1}{101}\right)\\ =3.\dfrac{99}{202}\\ =\dfrac{297}{202}\)

`5/6 +1/3 xx 2`

`=5/6 + 2/3`

`=5/6 +4/6`

`=9/6`

`=3/2`

`3/4 +x xx 3/2=2`

`x xx 3/2=2-3/4`

`x xx 3/2=5/4`

`x=5/4 : 3/2`

`x=5/6`

Đổi 1,2m=12dm

Thể tích khối gỗ đó là:

`12 xx 0,2 xx 1,5 = 36`(m³)
Khối gỗ đó cân nặng:

`36:2 xx1,6=28,8`(kg)

Đáp số: 28,8kg

`x+ 2/5 = 1/2`

`x=1/2 - 2/5`

`x= 5/10 - 4/10`

`x=1/10`

1. 3Fe + 2O₂ \(\underrightarrow{t^o}\)  Fe₃O₄ (hóa hợp)

2. Fe₂O₃ + 3CO →  2Fe + 3CO₂(thế)

3. MgCO₃→ MgO + CO₂(phân hủy)

4. 4Fe(OH)₂ + O₂ + 2H₂O  →  4Fe(OH)₃(hóa hợp)

5 . 2KClO₃ →  2KCl + 3O₂(phân hủy)

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