chuẩn 

b ơi minh thấy đề bài nó cứ kì kì

nếu như bn viết đề bài đúng thì mình có thể lm đc cho bn đó

\(\frac{3^2.3^8}{27^3}=3x=>\frac{3^{10}}{\left(3^3\right)^3}=3x=>\frac{3^{10}}{3^9}=3x=>3^{10-9}=3x=>3x=3=>x=1\)

Giữ lời hứa nka Nguyễn Mạnh Tân!

làm nhanh mình k cho

( 0,25x ) : 3 = 5/6 : 0,125

( 1/4x ) : 3 = 5/6 : 1/8

( 1/4x ) : 3 = 5/6 x 8

( 1/4x ) : 3 = 20/3

1/4x          = 20/3 x 3

1/4x         = 20

x              = 20 : 1/4

x              = 80

0,01 : 2,5 = ( 0,75x ) : 0,75

1/100 : 25/10 = (3/4x) : 3/4

1/100 x 10/25 = (3/4x) : 3/4

=>(3/4x) : 3/4 = 1/250

3/4x                = 1/250 x 3/4

3/4x                = 3/1000

x                     = 3/1000 : 3/4

x                     = 1/250

a: Sửa đề: \(3^{2x-1}+2\cdot9^{x-1}=405\)

=>\(3^{2x-1}+2\cdot3^{2x-2}=305\)

=>\(3^{2x-2+1}+2\cdot3^{2x-2}=405\)

=>\(5\cdot3^{2x-2}=405\)

=>\(3^{2x-2}=81=3^4\)

=>2x-2=4

=>2x=6

=>x=3

b: Ta có: \(\frac35\left(3x^3-\frac89\right)-\frac12\left(\frac32-1\right)=-\frac14\)

=>\(\frac35\left(3x^3-\frac89\right)-\frac12\cdot\frac12=-\frac14\)

=>\(\frac35\left(3x^3-\frac89\right)=-\frac14+\frac14=0\)

=>\(3x^3-\frac89=0\)

=>\(3x^3=\frac89\)

=>\(x^3=\frac{8}{27}=\left(\frac23\right)^3\)

=>\(x=\frac23\)

c: Ta có: \(\left(\frac13\right)^{x-1}+5\cdot\left(\frac13\right)^{x+1}=\frac{14}{9^3}\)

=>\(\left(\frac13\right)^{x-1}+5\cdot\left(\frac13\right)^{x-1}\cdot\frac19=\frac{14}{3^6}\)

=>\(\left(\frac13\right)^{x-1}\left(1+\frac59\right)=\frac{14}{3^6}\)

=>\(\left(\frac13\right)^{x-1}=\frac{14}{3^6}:\frac{14}{9}=\frac{9}{3^6}=\frac{1}{3^4}\)

=>x-1=4

=>x=5