Sai rồi bn ơi, đọc kĩ đề lại chút nhe Ơ x Ơ

Sai hết rồi Ơ x Ơ

Gọi số \(HS\) khối \(6\) là \(x\)

Vì khi xếp thành hàng \(18;\) hàng \(24;\) hàng \(21\) đều vừa đủ

Ta có \(x\) \(⋮\) \(18;\) \(x\) \(⋮\) \(24;\) \(x\) \(⋮\) \(21\)

Suy ra \(x\) \(\in\) \(BC (18,24,21)\)

\(18 = 2.3^2\)

\(24 = 2^3.3\)

\(21 = 3.7\)

\(BCNN (18,24,21) = 2^3.3^2.7\) \(= 504\)

\(BC (18,21,24) = \) \(\left\{0;504;1008;1620;...\right\}\)

Mà \(x\) là số tự nhiên có \(3\) chữ số

Vậy \(x = \) \(504\) 

\(\Rightarrow\) Vậy số \(HS\) khối \(6\) của trường đó có \(504\) \(HS\)

Oki Ơ w Ơ

\(4.\) Can you spell that, please?

Hoặc

Please can you spell that?

\(1 \)  Who do you grade?

\(2 \) There are 285 students in my school

\(3\)  She has long curly hair

Mà do \(30 < x < 100\) nên ta có

\(\Rightarrow\) \(x\) \(\in\) \(\left\{38;57;76;95\right\}\)

Oki Ơ w Ơ

\(x \) \(⋮\) \(19\) và \(30< x < 100\)

\(\Rightarrow\) \(x \) \(\in\) \(B(19)\) và \(30 < x < 100\)

\(\Rightarrow\) \(x \) \(\in\) \(\left\{0;19;38;57;76;95\right\}\)

\(a)\) 

\(Ư (6) = \) \(\left\{1;2;3;6\right\}\)

\(Ư\left(9\right)=\left\{1;3;9\right\}\)

\(Ư\left(12\right)=\left\{1;2;3;4;6;12\right\}\)

\(b)\)

\(Ư\left(7\right)=\left\{1;7\right\}\)

\(Ư\left(18\right)=\left\{1;2;3;6;9;18\right\}\)

\(Ư\left(10\right)=\left\{1;2;5;10\right\}\)

\(c)\)

\(Ư\left(15\right)=\left\{1;3;5;15\right\}\)

\(Ư\left(16\right)=\left\{1;2;4;8;16\right\}\)

\(Ư\left(250\right)=\left\{1;2;5;10;25;50;125;250\right\}\)

\(d)\)

\(B\left(23\right)=\left\{0;23;46;69;...\right\}\)

\(B\left(10\right)=\left\{0;10;20;30;...\right\}\)

\(B\left(8\right)=\left\{0;8;16;24;...\right\}\)

\(e)\)

\(B\left(3\right)=\left\{0;3;6;9;...\right\}\)

\(B\left(12\right)=\left\{0;12;24;36;...\right\}\)

\(B\left(9\right)=\left\{0;9;18;27;...\right\}\)

\(g)\)

\(B\left(18\right)=\left\{0;18;36;54;...\right\}\)

\(B\left(20\right)=\left\{0;20;40;60;...\right\}\)

\(B\left(14\right)=\left\{0;14;28;42;...\right\}\)