Question

bài 1 : rút gọn phân số P=\(\frac{9^4.27^3.24}{81^2.3^7.5^2}\)

bài 2 : chứng tỏ : \(\frac{1}{n\left(n+1\right)}=\frac{1}{n}-\frac{1}{n+1}\left(\curlyvee n\in N^{\text{*}}\right)\)

Answer 1

Bài 1 :

\(P=\frac{9^4.27^3.24}{81^2.3^7.5^2}=\frac{9^4.3^9.3.2^3}{9^4.3^7.3^2.2^3}=3\)

Bài 2 :

\(\frac{1}{n}-\frac{1}{n+1}=\frac{n+1}{n\left(n+1\right)}-\frac{n}{n\left(n+1\right)}=\frac{n+1-n}{n\left(n+1\right)}=\frac{1}{n\left(n+1\right)}\left(đpcm\right)\)

Answer 2

Bài 2 : Ta có : \(\frac{1}{n}-\frac{1}{n+1}=\frac{n+1}{n\left(n+1\right)}-\frac{n}{n\left(n+1\right)}=\frac{n+1-n}{n\left(n+1\right)}=\frac{1}{n\left(n+1\right)}\left(đpcm\right)\)

Answer 3

nhớ tick cho mk nhé

Answer 4

và theo dõi mk nhé