\(\left(2\dfrac{4}{5}.x-50\right):\dfrac{2}{5}=51\)

\(=>\dfrac{14}{5}.x-50=51.\dfrac{2}{5}\)

\(=>\dfrac{14}{5}.x-50=\dfrac{102}{5}\)

\(=>\dfrac{14}{5}.x=\dfrac{102}{5}+50\)

\(=>\dfrac{14}{5}.x=\dfrac{352}{5}\)

\(=>x=\dfrac{352}{5}:\dfrac{14}{5}=\dfrac{352}{5}.\dfrac{5}{14}\)

\(=>x=\dfrac{176}{7}\)

Vậy...

\(x\times27,5=83,05\)

\(=>x=83,05:27,5\)

\(=>x=3,02\)

\(8,72:x=21,8\)

\(=>x=8,72:21,8\)

\(=>x=0,4\)

Vậy...

`#NqHahh`

\(S=3+3^2+3^3+3^4+...+3^{2024}\)

\(S=\left(3+3^2+3^3\right)+\left(3^4+3^5+3^6\right)+...+\left(3^{2022}+3^{2023}+3^{2024}\right)\)

\(S=36+3^3.\left(3+3^2+3^3\right)+...+3^{2021}.\left(3+3^2+3^3\right)\)

\(S=36+3^3.36+...+3^{2021}.36\)

\(S=36.\left(1+3^3+...+3^{2021}\right)\)

Vì \(36⋮13\) nên \(36.\left(1+3^3+...+3^{2021}\right)⋮13\)

Vậy \(S⋮13\)

`#NqHahh`

Mike doesn't play chess as well as Barbara.

- SS hơn:

( Tính từ ngắn ) S + be + adj/ V + adv + er + than...

( Tính từ dài ) S + be +  more adj/ V + more adv/ V + er + than...

- SS bằng: S + be/ V + as + adj/ adv + as +...

Tạm dịch: Mike không chơi tốt bằng Barbara.

`#NqHahh`

\(y\times101-y=202:0,001\)

\(=>y\times\left(101-1\right)=202000\)

\(=>y\times100=202000\)

\(=>x=202000:100\)

\(=>x=2020\)

Vậy...

`#NqHahh`

Chú ý lớp ạ, lớp 2 mới học nhân bảng 2 và 5 thôi. Chưa học chia đâu bạn!

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