hình như là 3² chứ k f 3³

\(B=\frac{1^2}{1\cdot2}\cdot\frac{2^2}{2\cdot3}\cdot\frac{3^2}{3\cdot4}\cdot\frac{4^2}{4\cdot5}\)

\(B=\frac{\left(1\cdot1\right)\left(2\cdot2\right)\left(3\cdot3\right)\left(4\cdot4\right)}{\left(1\cdot2\right)\left(2\cdot3\right)\left(3\cdot4\right)\left(4\cdot5\right)}\)

\(B=\frac{\left(1\cdot2\cdot3\cdot4\right)\left(1\cdot2\cdot3\cdot4\right)}{\left(1\cdot2\cdot3\cdot4\right)\left(2\cdot3\cdot4\cdot5\right)}\)

\(=\frac{1}{5}\)

\(B=\frac{1^2}{1\cdot2}\cdot\frac{2^2}{2\cdot3}\cdot\frac{3^2}{3\cdot4}\cdot\frac{4^2}{4\cdot5}\)

\(B=\frac{1^2\cdot2^2\cdot3^2\cdot4^2}{1\cdot2\cdot2\cdot3\cdot3\cdot4\cdot4\cdot5}\)

\(B=\frac{1^2\cdot2^2\cdot3^2\cdot4^2}{1^2\cdot2^2\cdot3^2\cdot4^2\cdot5}=\frac{1}{5}\)

Kết quả là

  2^70 < 3 ^ 51

    ~~ Chúc bạn học tốt ~~

ghghghhghftghd

\(A=\left(\frac{1}{2016}+1\right)+\left(\frac{2}{2015}+1\right)+...+\left(\frac{2015}{2}+1\right)+1\)

     =    \(\frac{2017}{2016}+\frac{2017}{2015}+\frac{2017}{2014}+...\frac{2017}{2}+\frac{2017}{2017}\)

     =  \(2017\left(\frac{1}{2}+\frac{1}{3}+\frac{1}{4}+...+\frac{1}{2017}\right)\)

  \(\Rightarrow\frac{A}{B}=\frac{2017\left(\frac{1}{2}+\frac{1}{3}+\frac{1}{4}+...+\frac{1}{2017}\right)}{\frac{1}{2}+\frac{1}{3}+\frac{1}{4}+...+\frac{1}{2017}}\)

                = 2017

Chúc bạn học giỏi!

ghtyuhyui

107 < 73

CHÚC BẠN HỌC TỐT NHA !

107⁵⁰ = (107¹⁰)⁵

73⁷⁵ = (73⁵)⁵

Mà 107¹⁰ > 73⁵ ; 5 = 5

\(\Rightarrow\)107⁵⁰ > 73⁷⁵

\(\left(\frac{3}{2}-\frac{1}{2}x\right)\left(x^3-\frac{1}{4}x\right)=0\)

\(\Rightarrow\orbr{\begin{cases}\frac{3}{2}-\frac{1}{2}x=0\left(1\right)\\x^3-\frac{1}{4}x=0\left(2\right)\end{cases}}\)

Giải (1)

\(\frac{3}{2}-\frac{1}{2}x=0\)

\(\frac{1}{2}x=\frac{3}{2}\)

\(x=3\)

Giải (2)

\(x^3-\frac{1}{4}x=0\)

\(x\left(x^2-\frac{1}{4}\right)=0\)

\(\Rightarrow\orbr{\begin{cases}x=0\\x^2-\frac{1}{4}=0\left(3\right)\end{cases}}\)

      Giải (3)

\(x^2-\frac{1}{4}=0\)

\(x^2=\frac{1}{4}\)

\(\Rightarrow\orbr{\begin{cases}x=\frac{1}{2}\\x=-\frac{1}{2}\end{cases}}\)

Vậy, \(x\in\left\{-\frac{1}{2};\frac{1}{2}0;3\right\}\)

\(\left(\frac{3}{2}-\frac{1}{2}x\right).\left(x^3-\frac{1}{4}x\right)=0\)

\(\Rightarrow\orbr{\begin{cases}\frac{3}{2}-\frac{1}{2}x=0\\x^3-\frac{1}{4}x=0\end{cases}}\)

\(\Rightarrow\orbr{\begin{cases}-\frac{1}{2}x=\frac{3}{2}\\x.\left(x^2-\frac{1}{4}\right)=0\end{cases}}\)

\(\Rightarrow\orbr{\begin{cases}x=\frac{3}{2}\div\frac{-1}{2}\\x=0\div\left(x^2-\frac{1}{4}\right)\end{cases}}\)

\(\Rightarrow\orbr{\begin{cases}x=-3\\x=0\end{cases}}\)

vậy x = -3 hoặc x = 0

dê thế mà ko lam dc bang 215

hi hi

ta có: 1/2=1/1x2

          1/6=1/2x3

           1/12=1/3x4

             1/20=1/4x5

             1/30=1/5x6

                1/42=1/6x7

                 1/56=1/7x8

              1/72=1/8x9

               1/90=1/9x10

                1/110=1/10x11

              tiếp theo bn tiếp tục nhé

1/2+1/6+1/12+1/20+1/30+1/42+1/56+1/72+1/90+1/110

=1/1x2+1/2x3+1/3x4+1/4x5+1/5x6+1/6x7+1/7x8+1/8x9+1/9x10+1/10x1

=1-1/2+1/2-1/3+1/3-1/4+1/4-1/5+1/5-1/6+1/6-1/7+1/7-1/8+1/8-1/9+1/9-1/10+1/10-1/11

=1-1/11

=10/11