Cho x,y E R, $x+y=-3$

Tìm GTNN B = $x^4+y^4-x^3-y^3+2x^2y^2+2xy(x^2+y^2)+13xy$

`5dm6cm = 56cm`

`-> A`

My uncle isn't slim.He's overweight

Dịch 

`+` slim : mảnh khảnh

`+` tall : cao

`+` average height : chiều cao trung bình

`+` overweight : thừa cân

`-> A`

`a)` `2KMnO_4` $\xrightarrow[]{t^o}$ `K_2MnO_4 + MnO_2 + O_2`

`b) Fe + 2HCl -> FeCl_2 + H_2`

`c)` `2H_2O` $\xrightarrow[]{đpnc}$ `2H_2 + O_2`

`d) P_2O_5 + 3H_2O -> 2H_3PO_4`

`e) 2Zn + O_2` $\xrightarrow[]{t^o}$ `2ZnO`

ng ta kêu viết các pt, nếu ghi vậy, lỡ mất điểm uổng đấy ạ

thiếu pt kìa

Câu `3`

`a)`

`PTHH :`

`C_2H_4+3O_2 ->^{t^o} 2CO_2 + 2H_2O`

`CO_2 + Ca(OH)_2 -> CaCO_3 + H_2O`

`b)`

`n_{C_2H_4} = {14}/{28} = 0,5(mol)`

`n_{O_2} = 3n_{C_2H_4} = 0,5.3 = 1,5(mol)`

`-> V_{O_2} = 1,5.22,4 = 33,6l`

Câu 5

`a)n_{Mg} = {8,4}/{24} = 0,35(mol)`

`PTHH : Mg + H_2SO_4 -> MgSO_4 + H_2`

`n_{H_2} = n_{Mg} = 0,35(mol)`

`-> V_{H_2} = 0,35.22,4 = 7,84(gam)`

`n_{MgSO_4} = n_{Mg} = 0,35(mol)`

`-> m_{MgSO_4} = 0,35.120 = 42(gam)`

`b)H_2 + CuO ->^{t^o} Cu + H_2O`

`n_{CuO} = n_{H_2} = 0,35(mol)`

`-> m_{CuO} = 0,35.80 = 28(gam)`

`n_{Cu} = n_{H_2} = 0,35(mol)`

`-> m_{Cu} = 0,35.64 = 22,4(gam)`

$ a) PTHH:\\ 2CH_3COOH + Zn \to (CH_3COO)_2Zn + H_2 \\ b) n_{H_2} = \dfrac{2,688}{22,4} = 0,12(mol) \\$

$ \to n_{CH_3COOH} = 2n_{H_2} = 0,24(mol) $

`%m_{CH_3COOH} = {0,24.60}/{30}.100% = 48%`

` %m_{C_2H_5OH} = 100 - 48 = 52%`

` n_{(CH_3COO)_2Zn} = n_{H_2} = 0,12(mol) `

` \to m_{(CH_3COO)_2Zn} = 0,12.183 = 21,96(gam)`

They still decided to buy that car despite lacking some money

$\to$ Although they lack some money,they still decided to buy that car.