Mn giải hộ mình với
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I know many festivals but the one I like the most is Tet. It is the most important festival in Vietnam. Tet is celebrated every year on January 1 of the lunar calendar. When Tet comes, we are 1 year old. Before Tet, family members will go to buy food, fruit, and flowers. And they also buy decorations and cherry blossom lines. People will decorate the house, and they will place the potted peach blossom tree in the right front position of the house. They also make banh chung, the traditional dish of our country. During Tet, everyone in the family will gather together and tell each other about the past years in order to enter a better New Year together. They will eat the same banh chung. After that, we will visit relatives and neighbors. And our children will receive lucky money. On New Year's Eve, everyone can watch the colorful fireworks in the sky together. I love Tet, every year I look forward to Tet, to see my loved ones again
Diện tích các cửa là:
0,16*8,5*6=8,16m2
Diện tích cần quét vôi là:
(8,5+6)*2*4,2+8,5*6-8,16=164,64m2
Bài 5:
CTPT: CxHyO
\(n_{CaCO_3}=\dfrac{40}{100}=0,4\left(mol\right)\)
PTHH: 2CxHyO + \(\dfrac{4x+y-2}{2}\)O2 --to--> 2xCO2 + yH2O
\(\dfrac{0,4}{x}\)<--\(\dfrac{0,4\left(4x+y-2\right)}{4x}\)<------0,4
Ca(OH)2 + CO2 --> CaCO3 + H2O
0,4<-----0,4
=> \(M_{C_xH_yO}=\dfrac{7,4}{\dfrac{0,4}{x}}=18,5x\left(g/mol\right)\)
=> y + 16 = 6,5x (1)
Có \(n_{O_2}=\dfrac{19,2}{32}=0,6\left(mol\right)\)
=> \(\dfrac{0,4\left(4x+y-2\right)}{4x}=0,6\)
=> 0,8x = 0,4y - 0,8 (2)
(1)(2) => x = 4; y = 10
CTPT: C4H10O
bài 7
\(x^{n+2}-x^n\)
\(=x^{n+2-n}=x^2\)
\(\left(b\right)x^{x+3}-x^{x+1}=x^{x+3-x-1}=X^2\)
c)
\(x^{2m}+x^m=x^{2m+m}=x^{2m}\)
d)
\(x^{2n+1}-x^{4n}=x^{2n+1-4n}=x^{1-2n}\)
Vui lòng bạn ko đăng bài thi