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6 tháng 3 2022

CaC2+2H2O->C2H2+Ca(OH)2

C2H2+H2-to>C2H4

C2H2+2H2-to>C2H6

C2H4+Br2->C2H4Br2

n-(CH2=CH2-)--to>-(CH2-CH2)-n

21 tháng 7 2021

1. I was given a notebook as a reward by my teacher.

2. Grapes are picked and then turned into wine.

3. I wasn't allowed to stay up late by my father.

4. Pencils aren't used in your Maths exam.

5. I was allowed to go picnic with my friends by my parents yesterday.

6. I wasn't told about his story.

7. This cake is made by me.

8. When I was a child, my leg was bitten by a dog.

9. Many social skills are needed when you enter the workplace.

21 tháng 7 2021

1, I was given a notebook by my teacher as a reward

  or A notebook  was given to me  by my teacher as a reward

2, Grapes are picked and wine is turned into

3, I am not allowed to stay up late by my father

4, pencils are not used  in your maths

5, i was not allowed to go picnic with my friends by my parents yesterday

6, i was not told about his story

7, this cake was made by me

8,  When I was a kid, my leg was bitten by a dog

9, many social kills are needed when the workplace is entered

10 tháng 3 2022

\(x\times4+\frac{1}{2}\times x=55,35\)

\(\Leftrightarrow x\times\left(4+\frac{1}{2}\right)=55,35\)

\(\Leftrightarrow x\times4,5=55,35\)

\(\Leftrightarrow x=55,35:4,5\)

\(\Leftrightarrow x=12,3\)

Vậy x= 12,3

10 tháng 3 2022

x.4+1/2.x=55,35
x.(4+1/2)=55.35
x.9/2=55,35
x=55,35:9/2
x=12,3
vì là máy ko có dấu nhân nên thay dấu nhân là dấu chấm

a: \(=\left(2a^2-3a^2-4a^2\right)+\left(-0.5a-2.5a+3a\right)+\left(5-4+7\right)=-5a^2+8\)

b: \(=\left(a^3-a^3\right)+\left(-2a^2-3a^2+4a^2\right)+\left(a+a-a\right)+\left(-5+4\right)=-a^2+a-1\)

c: \(=-b^4+3b^2-3b-1-b^3+1-3b^2+b^4-5+4b^3+5\)

\(=3b^3-3b\)

7 tháng 1 2022

33A

34B

35C

36D

37D

38A

39B

40.Natri

16 tháng 2 2022

1.B 2.C nha

16 tháng 2 2022

B

C

S ABD/S BCD=AB/CD=1/3

=>S BCD=45cm2

=>S ABCD=60cm2

a: 13/35=1/5+1/7+1/35

b: 17/63=1/9+1/7+1/63

 

19 tháng 2 2022

a: 13/35=1/5+1/7+1/35

b: 17/63=1/9+1/7+1/63

a: 1-1/2=1/2

b: 1-3/10=7/10

c:3-1/3=8/3

d: 4-1/9=35/9

e: 8-2/3=22/3

f: 5-2/5=23/5

25 tháng 5 2022

a: bằng 1 phần 2

b: bằng 7 phần 10

c: bằng 2 phần 3

d:bằng 35 phần 9

e: bằng 22 phần 3

g: bằng 23 phần 5

chúc bn học tốt

 

Tổng hai phân số ban đầu là

7/9+1/5=35/45+9/45=44/45

19 tháng 2 2022

7/9+1/5=35/45+9/45=44/45