rút gọn hả?

hok mà thực hiện phép tính

- A ở trên giữa các phân số là dấu " + " nha mấy bạn !

\(A=\frac{4}{3}.\frac{13}{9}-\frac{4}{3}.\frac{40}{9}\)

\(=\frac{4}{3}\left(\frac{13}{9}-\frac{40}{9}\right)\)

\(=\frac{4}{3}.\frac{-27}{9}\)

\(=-4\)

Vậy   \(25\%\) của   \(A\) là:       \(\left(-4\right).25\%=-1\)

\(\left(5^x-1\right).3-2=70\)

\(\Rightarrow\left(5^x-1\right).3=70+2\)

\(\Rightarrow\left(5^x-1\right).3=72\)

\(\Rightarrow5^x-1=72:3\)

\(\Rightarrow5^x-1=24\)

\(\Rightarrow5^x=24+1\)

\(\Rightarrow5^x=25\)

\(\Rightarrow5^x=5^2\)

\(\Rightarrow x=2\)

(5^x  -1 ).3 - 2 = 70

=> (5^x - 1) .3 = 72

=>(5^x -1 )= 24

=> 5^x -1 = 24

=> 5^x   = 25

<=>  x = 2 

Đề có đúng không vậy bạn?

2010.2009-1 / 2008 - 2010 + 2009

2010 - 2010 + 2009 - 2009 . 1/2008

= 0+0. 1/2008

= 0 

k mk na <3

\(S=\frac{1}{18}+\frac{1}{54}+\frac{1}{108}+...+\frac{1}{990}\)

\(=\frac{1}{3.6}+\frac{1}{6.9}+\frac{1}{9.12}+....+\frac{1}{30.33}\)

\(=\frac{1}{3}\left(\frac{3}{3.6}+\frac{3}{6.9}+\frac{3}{9.12}+...+\frac{3}{30.33}\right)\)

\(=\frac{1}{3}\left(\frac{1}{3}-\frac{1}{6}+\frac{1}{6}-\frac{1}{9}+\frac{1}{9}-\frac{1}{12}+...+\frac{1}{30}-\frac{1}{33}\right)\)

\(=\frac{1}{3}\left(\frac{1}{3}-\frac{1}{33}\right)\)

\(=\frac{1}{3}.\frac{10}{33}=\frac{10}{99}\)

2^31 = 2^30 x 2 = ( 2^3 )^10 x 2 = 8^10 x 2 

3^21 = 3^20 x 3 = ( 3^2 )^10 x 3 = 9^10 x 3 

Vì 8^10 < 9^10 ; 2 < 3 

Nên 2^31 < 3^21 

thanks you very much !!!!!!!!!!!!!!!!!