bang 2 nhé

D=1+3-5-7+9+11....-397-399

1+3+5+7+...-397-399

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Chép sai đề

Ta có: C = (1.5.6+2.10.12+4.20.24+..+9.45.54):(1.3.5+2.6.10+4.12.20+...+9.27.45)

             = (1.3.5.2+2.6.10.2+4.12.20.2+...+9.27.45.2):(1.3.5+2.6.10+4.12.20+...+9.27.45)

             = (2.(1.3.5+2.6.10+4.12.20+...+9.27.45)):(1.3.5+2.6.10+4.12.20+...+9.27.45)

             =2

 Bằng 2 nhé

Bằng 2 bạn nhé

k cho mk dc k.đi..................................................

\(\frac{1\cdot5\cdot6+2\cdot10\cdot12+4\cdot20\cdot24+9\cdot45\cdot54}{1\cdot3\cdot5+2\cdot6\cdot10+4\cdot12\cdot20+9\cdot27\cdot45}=\frac{1\cdot5\cdot6\cdot\left(1+2+4+9\right)}{1\cdot3\cdot5\cdot\left(1+2+4+9\right)}=2\)

Ta có:

\(C=\frac{1.5.6+2.10.12+4.20.24+...+9.45.54}{1.3.5+2.6.10+4.12.20+...+9.27.45}\)

     \(=\frac{1.3.5.2+2.6.10.2+4.12.20.2+...+9.27.45.2}{1.3.5+2.6.10+4.12.20+...+9.27.45}\)

     \(=\frac{\left(1.3.5+2.6.10+4.12.20+...+9.27.45\right).2}{1.3.5+2.6.10+4.12.20+...+9.27.45}\)

     \(=2\)

Vậy C=2.

\(A=\frac{1.5.6+2.10.12+4.20.24+9.45.54}{1.3.5+2.6.10+4.12.20+9.27.45}\)

\(A=\frac{1.5.6.\left(1^3+2^3+4^3+9^3\right)}{1.3.5.\left(1^3+2^3+4^3+9^3\right)}=2\)

A=\(\frac{1.5.6+8\left(1.5.6\right)+64\left(1.5.6\right)+...+729\left(1.5.6\right)}{1.3.5+8\left(1.3.5\right)+64\left(1.3.5\right)+...+729\left(1.3.5\right)}\)

  =\(\frac{\left(1.5.6\right)\left(1+8+64+...+729\right)}{\left(1.3.5\right)\left(1+8+64+...+729\right)}\)

  =\(\frac{1.5.6}{1.3.5}\)

 =2