M.N giúp mk lên 120sp nha
MK cảm ơn M.N nhiều lắm ạ!!!
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Những câu hỏi liên quan
NV
Nguyễn Việt Lâm
Giáo viên
15 tháng 4 2022
Vận tốc của chất điểm:
\(v\left(t\right)=s'\left(t\right)=3t^2-6t+9=3\left(t-1\right)^2+6\ge6\)
Dấu "=" xảy ra khi \(t-1=0\Rightarrow t=1s\)
DN
15 tháng 4 2022
Dạ em cảm ơn rất nhiều ạ, nhưng nếu được thầy có thể giải thích giúp em làm sao ra đc :S'(t) ạ ?
R
7
10 tháng 5 2019
47 . 3 = 141
55 . 11 = 605
77 . 2 - 154 = 0
T.i.c.k mình nha.MÌnh rùi đó.
24 tháng 8 2021
a)
\(n_{Fe_2O_3}=\dfrac{24}{160}=0,15\left(mol\right)\\ n_{H_2SO_4}=0,2.2,5=0,5\left(mol\right)\\ PTHH:Fe_2O_3+3H_2SO_4\rightarrow Fe_2\left(SO_4\right)_3+3H_2O.\\ Vì:\dfrac{0,15}{1}< \dfrac{0,5}{3}\)
=> H2SO4 dư, Fe2O3 hết => Tính theo Fe2O3
Ta có:
\(n_{H_2SO_4\left(dư\right)}=0,5-\left(0,15.3\right)=0,05\left(mol\right)\\ \Rightarrow m_{H_2SO_4\left(dư\right)}=0,05.98=4,9\left(g\right)\)
b) \(n_{Fe_2\left(SO_4\right)_3}=n_{Fe_2O_3}=0,15\left(mol\right)\)
=> \(m_{Fe_2\left(SO_4\right)_3}=0,15.400=60\left(g\right)\)
c) \(V_{ddFe_2\left(SO_4\right)_3}=V_{ddH_2SO_4}=200\left(ml\right)=0,2\left(l\right)\)
Vậy: \(C_{MddFe_2\left(SO_4\right)_3}=\dfrac{0,15}{0,2}=0,75\left(M\right)\)
UT
24 tháng 8 2021
nFe2O3= 24/160 = 0,15 mol
nH2SO4 = 0,2.2,5= 0,5 mol
Fe2O3 + 3H2SO4 -> Fe2(SO4)3 + 3H2O
0,15 0,5
ta có 0,15/1 < 0,5/3
=> H2SO4 dư
Fe2O3 +3H2SO4 -> Fe2(SO4)3 +3H2O
0,15 0,45 0,15
nH2SO4 dư = 0,5-0,45=0,05mol
mH2SO4 dư = 05.98=4,9(g)
b, mFe2(SO4)3 = 0,15.400=60(g)
c, C(Fe2(SO4)3) = n/V = 0,15/ 0,2=0,75M
C(H2SO4) dư = n/V = 0,05/0,2= 0,25 M
8 tháng 7 2021
Câu 9: B
Câu 10: B
Câu 11: A
Câu 12: D
Câu 13: C
Câu 14: A
Câu 15: C
CB
26 tháng 10 2021
Tham khảo!
There are many advantages and disadvantages of choosing to live in the country or to live in the city. But the advantages of living in the country definitely outweigh the advantages of living in the city.
In the city, public schools are often packed full of students resulting in larger class sizes and no real teacher student relationship. You would be lucky if your teacher could put a name to your face. Though, bigger schools in the city offer more courses for the student to take and also offer more extracurricular activities. Where in the country, public schools often do not have many students making class sizes significantly smaller resulting in a better teacher student relationship. Your teacher usually knows you by first and last name, and chances are, your teacher had a few of your family members as students. Though these things are advantages, school in rural areas generally do not offer as many courses and also do not have as many extracurricular activities to be involved in, limiting the students to fewer opportunities.
There are a lot of activities to do in the city. There are more movie theaters, concerts, professional sporting events, zoos, shopping malls, restaurants and museums. But the activities you can do in the country are a lot more fun. In the country, activities consist of, four wheeling, boating, horseback riding, camping, having bon fires, taking walks in the woods and having back yard barbeques.
Transportation is very accessible in the city. Public transportation, by way of subways, busses, trams and ferries are easy and cheap ways of getting around. But the streets are also very crowded. Whereas owning your own vehicle is a must if you live in the country. Which, when added to the cost of insurance, gas and the time of commuting, can end up being a very large expense. But, with the roads being less crowded, it is a much more peaceful way to travel.
Some may believe that you have to...
LD
2
2 tháng 1 2023
\(x^2+4x+3=x^2+3x+x+3=\left(x^2+3x\right)+\left(x+3\right)=x\left(x+3\right)+\left(x+3\right)=\left(x+3\right)\left(x+1\right)\)
2 tháng 1 2023
m.n giúp mk câu này vs ạ
(\(\dfrac{x+2}{x-2}-\dfrac{x-2}{x+2}+\dfrac{16}{4-x^2}\)) : (\(\dfrac{4}{2-x}-\dfrac{8}{2x-x^2}\))
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tk mk với nha.mk xin đó
Mấy bn tk cho mk ik .rồi mk cho mỗi người 3 tk