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17 tháng 6 2015

(1/2)1500=(1/26)250=(1/64)250

Do 1/16>1/64 =>(1/16)250>(1/64)250

Vậy (1/16)250>(1/2)1500

17 tháng 6 2015

\(\left(\frac{1}{16}\right)^{250}\) và \(\left(\frac{1}{2}\right)^{1500}\)

=> \(\left(\frac{1}{16}\right)^{250}\) và \(\left(\left(\frac{1}{2}\right)^6\right)^{250}\)

=> \(\frac{1}{16}\) và \(\left(\frac{1}{2}\right)^6\)

=> \(\frac{1}{16}\) và \(\frac{1}{64}\)

=>  \(\frac{1}{16}\) >  \(\frac{1}{64}\)  hay  \(\left(\frac{1}{16}\right)^{250}\) >  \(\left(\frac{1}{2}\right)^{1500}\)

 

22 tháng 9 2019

3)

\(\left(\frac{1}{2}\right)^{x+1}=\frac{1}{16}\)

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

\(x+1=4\)

\(x=4-1\)

\(x=3\)

Vậy \(x=3.\)

Chúc bạn học tốt!

15 tháng 10 2019

Ta có:

\(\left(\frac{1}{16}\right)^{250}=\left(\frac{1}{16}\right)^{250}.\)

\(\left(\frac{1}{2}\right)^{1500}=\left[\left(\frac{1}{2}\right)^6\right]^{250}=\left(\frac{1}{64}\right)^{250}.\)

\(\frac{1}{16}>\frac{1}{64}\) nên \(\left(\frac{1}{16}\right)^{250}>\left(\frac{1}{64}\right)^{250}.\)

\(\Rightarrow\left(\frac{1}{16}\right)^{250}>\left(\frac{1}{2}\right)^{1500}.\)

Chúc bạn học tốt!

15 tháng 2 2015

x=[(1/2)^3]^75 =>(1/8)^75

y=[(1/3)^2]^75 =>(1/9)^75

vì 1/8>1/9

=>(1/2)^225  >  (1/3)^150

30 tháng 8 2016

Đặt \(100=n\) , ta có :

\(B=\left(\frac{1}{2^2}-1\right)\left(\frac{1}{3^2}-1\right)....\left(\frac{1}{n^2}-1\right)\)

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

    \(=\frac{\left(-1\right).\left(-2\right)....\left(1-n\right)}{2.3.....n}.\frac{3.4........\left(1+n\right)}{2.3.....n}\)

     \(=\frac{\left(-1\right).2.3.....\left(n-1\right)}{2.3......n}.\frac{3.4.....\left(n+1\right)}{2.3.......n}\)

     \(=\frac{\left(-1\right)}{n}.\frac{n+1}{2}=\frac{-1}{2}.\frac{n+1}{n}< \frac{-1}{2}\)

Vậy \(B< \frac{-1}{2}\)

25 tháng 9 2019

Bài 2:

Ta có: \(\frac{\left(3^3\right)^2.\left(2^3\right)^5}{\left(2.3\right)^6.\left(2^5\right)^3}\)\(=\frac{3^6.2^{15}}{2^6.3^6.2^{15}}\)\(\frac{1}{2^6}=\frac{1}{64}\)

Chúc hk tốt nha!!!

14 tháng 6 2018

Giải:

\(C=\left(1-\dfrac{2}{2.3}\right)\left(1-\dfrac{2}{3.4}\right)\left(1-\dfrac{2}{4.5}\right)...\left(1-\dfrac{2}{n\left(n+1\right)}\right)\)

Đk: \(n\ne0;n\ne-1\)

\(C=\left(1-\dfrac{2}{2.3}\right)\left(1-\dfrac{2}{3.4}\right)\left(1-\dfrac{2}{4.5}\right)...\left(1-\dfrac{2}{n\left(n+1\right)}\right)\)

\(\Leftrightarrow C=\left(\dfrac{2.3-2}{2.3}\right)\left(\dfrac{3.4-2}{3.4}\right)\left(\dfrac{4.5-2}{4.5}\right)...\left(\dfrac{n\left(n-1\right)-2}{n\left(n+1\right)}\right)\)

\(\Leftrightarrow C=\dfrac{4}{2.3}.\dfrac{10}{3.4}.\dfrac{18}{4.5}...\left(\dfrac{n\left(n-1\right)-2}{n\left(n+1\right)}\right)\)

\(\Leftrightarrow C=\dfrac{1.4}{2.3}.\dfrac{2.5}{3.4}.\dfrac{3.6}{4.5}...\left(\dfrac{\left(n-1\right)\left(n+2\right)}{n\left(n+1\right)}\right)\)

\(\Leftrightarrow C=\dfrac{1.4.2.5.3.6...\left(n-1\right)\left(n+2\right)}{2.3.3.4.4.5.n\left(n+1\right)}\)

\(\Leftrightarrow C=\dfrac{\left[1.2.3...\left(n-1\right)\right]\left[4.5.6\left(n+2\right)\right]}{\left(2.3.4...n\right)\left[3.4.5....\left(n+1\right)\right]}\)

\(\Leftrightarrow C=\dfrac{n+2}{3n}\)

\(\dfrac{n+2}{3n}< \dfrac{2n+2}{3n}\)

\(\Leftrightarrow C< \dfrac{2n+2}{3n}\)

Vậy ...

14 tháng 6 2018

Giải:

\(C=\left(1-\dfrac{2}{2.3}\right)\left(1-\dfrac{2}{3.4}\right)\left(1-\dfrac{2}{4.5}\right)...\left(1-\dfrac{2}{n\left(n+1\right)}\right)\)

Đk: \(n\ne0;n\ne-1\)

\(C=\left(1-\dfrac{2}{2.3}\right)\left(1-\dfrac{2}{3.4}\right)\left(1-\dfrac{2}{4.5}\right)...\left(1-\dfrac{2}{n\left(n+1\right)}\right)\)

\(\Leftrightarrow C=\left(\dfrac{2.3-2}{2.3}\right)\left(\dfrac{3.4-2}{3.4}\right)\left(\dfrac{4.5-2}{4.5}\right)...\left(\dfrac{n\left(n-1\right)-2}{n\left(n+1\right)}\right)\)

\(\Leftrightarrow C=\dfrac{4}{2.3}.\dfrac{10}{3.4}.\dfrac{18}{4.5}...\left(\dfrac{n\left(n-1\right)-2}{n\left(n+1\right)}\right)\)

\(\Leftrightarrow C=\dfrac{1.4}{2.3}.\dfrac{2.5}{3.4}.\dfrac{3.6}{4.5}...\left(\dfrac{\left(n-1\right)\left(n+2\right)}{n\left(n+1\right)}\right)\)

\(\Leftrightarrow C=\dfrac{1.4.2.5.3.6...\left(n-1\right)\left(n+2\right)}{2.3.3.4.4.5.n\left(n+1\right)}\)

\(\Leftrightarrow C=\dfrac{\left[1.2.3...\left(n-1\right)\right]\left[4.5.6\left(n+2\right)\right]}{\left(2.3.4...n\right)\left[3.4.5....\left(n+1\right)\right]}\)

\(\Leftrightarrow C=\dfrac{n+2}{3n}\)

\(\dfrac{n+2}{3n}< \dfrac{2n+2}{3n}\)

\(\Leftrightarrow C< \dfrac{2n+2}{3n}\)

Vậy ...