K
Khách

Hãy nhập câu hỏi của bạn vào đây, nếu là tài khoản VIP, bạn sẽ được ưu tiên trả lời.

20 tháng 7 2022

Bài 3:

\(M_A=11.4=44\left(g/mol\right)\)

\(M_B=0,5.32=16\left(g/mol\right)\)

Bài 4:

a) \(m_{Al}=1,5.27=40,5\left(g\right)\)

b) \(m_{H_2}=0,5.2=1\left(g\right)\)

c) \(m_{NaCl}=0,25.58,5=14,625\left(g\right)\)

d) \(m_{H_2O}=0,05.18=0,9\left(g\right)\)

Bài 5:

a) \(n_{khí}=\dfrac{4,4}{44}+\dfrac{0,4}{2}+\dfrac{5,6}{28}=0,5\left(mol\right)\)

b) \(V_{khí}=0,5.22,4=11,2\left(l\right)\)

 

`@` `\text {Ans}`

`\downarrow`

`1/3+6/9+4/5+5/25`

`= 1/3+2/3+4/5+1/5`

`= 1+1`

`= 2`

`4/7*2/5+4/7*3/5-1/7`

`= 4/7*(2/5+3/5)-1/7`

`= 4/7*1-1/7`

`= 4/7-1/7=3/7`

24 tháng 6 2023

.....................................................

24 tháng 8 2023

a) \(...=-\dfrac{1}{4}.\dfrac{4}{17}.\left(-\dfrac{63}{21}\right).\left(-\dfrac{7}{12}\right)\)

\(=-\dfrac{1}{17}.\dfrac{63}{21}.\dfrac{7}{12}\)

\(=-\dfrac{7}{68}\)

b) \(...=-\dfrac{2}{5}.\dfrac{4}{15}-\dfrac{3}{10}.\dfrac{4}{15}\)

\(=\dfrac{4}{15}\left(-\dfrac{2}{5}-\dfrac{3}{10}\right)\)

\(=\dfrac{4}{15}\left(-\dfrac{4}{10}-\dfrac{3}{10}\right)\)

\(=\dfrac{4}{15}.\left(-\dfrac{7}{10}\right)=-\dfrac{14}{75}\)

c) \(...=21-\dfrac{15}{4}:\left(\dfrac{9}{24}-\dfrac{4}{24}\right)\)

\(=21-\dfrac{15}{4}:\dfrac{5}{24}\)

\(=21-\dfrac{15}{4}.\dfrac{24}{5}\)

\(=21-3.6=3\)

d) \(...=\left(-\dfrac{3}{4}+\dfrac{2}{5}\right).\dfrac{7}{3}+\left(\dfrac{3}{5}-\dfrac{1}{4}\right).\dfrac{7}{3}\)

\(=\dfrac{7}{3}\left(-\dfrac{3}{4}+\dfrac{2}{5}+\dfrac{3}{5}-\dfrac{1}{4}\right)\)

\(=\dfrac{7}{3}\left(-\dfrac{3}{4}-\dfrac{1}{4}+\dfrac{2}{5}+\dfrac{3}{5}\right)\)

\(=\dfrac{7}{3}\left(-1+1\right)=0\)

10 tháng 4 2017

4/5(15+2/3)-4/5(20+2/3)=188/15-6/155=1162/93

10 tháng 4 2017

\(\frac{4}{5}\left(15+\frac{2}{3}\right)-\frac{4}{5}\left(20+\frac{2}{3}\right)\)

\(=\frac{4}{5}\left[\left(15+\frac{2}{3}\right)-\left(20+\frac{2}{3}\right)\right]\)

\(=\frac{4}{5}.\left(15+\frac{2}{3}-20-\frac{2}{3}\right)\)

\(=\frac{4}{5}.\left(-5\right)\)

\(=-4\)

14 tháng 10 2018

A=(2/7 + 5/7)+(1/4+3/4)+3/5

A=1+1+3/5

A=2+3/5

A=13/5

1 + 1 = 2

2 + 2 = 4 

3 + 3 = 6

4 + 4 = 8

5 + 5 = 10

ĐỔI TK NHA

17 tháng 4 2019

2

4

6

8

10

Mk sẽ giúg

18 tháng 2 2022

(3/5+2/5)+(4/9+5/9)=1+1=2

(5/4+3/4)+(3/8+5/8)=8/4+1=8/4  

20 tháng 7 2023

\(\dfrac{3}{2}\)(\(x\) - \(\dfrac{5}{3}\)) - \(\dfrac{4}{5}\) = \(x\) + 1

\(\dfrac{3}{2}\) \(x\) - \(\dfrac{15}{6}\) - \(\dfrac{4}{5}\) = \(x\) + 1

\(\dfrac{3}{2}\)\(x\) - \(x\)          = 1 + \(\dfrac{15}{6}\) + \(\dfrac{4}{5}\)

\(\dfrac{1}{2}\)\(x\)                 =\(\dfrac{43}{10}\)

    \(x\)                 = \(\dfrac{43}{10}\) \(\times\) 2

     \(x\)                = \(\dfrac{43}{5}\)

 

\(\dfrac{3}{2}\left(x-\dfrac{5}{3}\right)-\dfrac{4}{5}=x+1\\ \Rightarrow\dfrac{3.\left(x-\dfrac{5}{3}\right)}{2}-\dfrac{4}{5}=x+1\\ \Rightarrow\dfrac{3x-5}{2}-\dfrac{4}{5}=x+1\Rightarrow\dfrac{5\left(3x-5\right)}{10}-\dfrac{8}{10}=x+1\\ \Rightarrow\dfrac{15x-33}{10}=x+1\\ \Rightarrow\dfrac{15x-33}{10}-x=x+1\\ \Rightarrow\dfrac{15x-33}{10}=x+1-x\\ \Rightarrow5x-33=10\\ \Rightarrow5x=10+33\\\Rightarrow5x=43\\ \Rightarrow x=\dfrac{43}{5} \)

17 tháng 8 2023

a) 0

b) 0

c) 0

d) 0

28 tháng 8 2021

KHO THE

19 tháng 9 2021

\(A=\frac{\left[\left(25-1\right):1+1\right]\left(25+1\right)}{2}=325.\)

\(B=\frac{\left[\left(51-3\right):2+1\right]\left(51+3\right)}{2}=675\)

\(C=\frac{\left[\left(81-1\right):4+1\right]\left(81+1\right)}{2}=861\)