BTKL: \(a=\Sigma m_{O_2}=m_{hh\text{ oxit}}-m_{hh\text { KL}}=14,2-7,8=6,4(g)\)

48. My brother whose house was broken in called the police.

49. Mary was too very tired to study more.

50.If Emily wasn't sick today, she could go to school.

51.Although my grandparents are very busy, they spend a lot of time taking care of us.

52. The floor hasn't been cleaned yet.

53.We haven't seen our grandfather for five month.

54. I wish I could remember the answers to these questions.

55. I spent three hours cleaning the house yesterday. 

P8. 48.My brother whose house was broken in called the police.

49. Mary was too tired to study.

50. If Emily wasn't sick today, she could go to school.

51. Although my grandparents are very busy, they spend a lot of time taking care of us.

P9. 52. The floor hasn't been cleaned yet.

53.We haven't seen our grandfaather for five months.

54. I wish I could remember the answer to these questions.

55. I spent three hours cleaning the house yesterday.

Đề bài yêu cầu gì?

\(m_{HCl\left(1\right)}=600.2,5\%=15g\\ m_{HCl\left(2\right)}=400.15\%=60g\\ C\%_{HCl.sau}=\dfrac{75}{1000}\cdot100\%=7,5\%\)

Số các số hạnh là : ( 197 - 1 ) : 2 + 1 = 100 ( số )

Tổng là : ( 197 + 1 ) x 100 : 2 = 9900

Học tốt~

kết quả = 9801

dấu nhân mình thay bằng dấu chấm nhé!

khoảng cách là 2

số số hạng là:(197-1):2+1=99(số hạng)

Tổng là: 99.(197+1):2=9801

.

Ta có : \(T=1+2^2+2^4+2^6+....+2^{100}\)

\(\Rightarrow2^2\cdot T=2^2+2^4+2^6+2^8+....+2^{102}\)

\(\Rightarrow4T-T=\left(2^2+2^4+2^6+...+2^{102}\right)-\left(1+2^2+2^4+...+2^{100}\right)\)

\(\Rightarrow3T=2^{102}-1\Rightarrow T=\frac{2^{102}-1}{3}\)

Anh làm rồi em nhé