\(3^{x+4}=9^{2x-1}\)

\(\Rightarrow3^{x+4}=3^{4x-2}\)

\(\Rightarrow x+4=4x-2\)

\(\Rightarrow3x=6\Rightarrow x=2\)

Thank you

a)=1/2 . 8/15 - 3/4.47/9

=4/15 - 47/12

=-73/20

b)=2-1/3 . -21/20

=2+7/20

=47/20

\(\left[7\times13+8\times13\right]:\left[9\frac{2}{3}-y\right]=39\)

\(\left[\left(7+8\right)\times13\right]:\left[\frac{29}{3}-y\right]=39\)

\(\left[15\times13\right]:\left[\frac{29}{3}-y\right]=39\)

\(195:\left[\frac{29}{3}-y\right]=39\)

\(\frac{29}{3}-y=195:30\)

\(\frac{29}{3}-y=\frac{13}{2}\)

\(y=\frac{29}{3}-\frac{13}{2}\)

\(y=\frac{19}{6}\)

Học tốt #

[ 7 x 13 + 8 x 13 ] : [ \(9\frac{2}{3}\) - y ] = 39

[ 13 x ( 7 + 8 )]     :  [ \(9\frac{2}{3}\)- y  ]  = 39

[ 13 x 15 ]            :  [\(9\frac{2}{3}\) - y  ]   = 39

195                      : [\(\frac{29}{3}\)  - y  ]   = 39

                              [ \(\frac{29}{3}\) - y  ]   = 195 : 39 (^*1 )

                              [\(\frac{29}{3}-y\)]  = 5

                            y                         = \(\frac{29}{3}-5\)

                           y                          = \(\frac{14}{3}\)

2(x-4)-(x+5)=-13

2x-8-x-5     =-13

2x-x           =-13+5+8

          x     =0

a) \(\left(\frac{4}{13}.\frac{6}{5}+\frac{4}{13}.\frac{2}{5}\right).\left(2x+1\right)^2=\frac{10}{13}\)

\(\left(\frac{4}{13}.\frac{8}{5}\right).\left(2x+1\right)^2=\frac{10}{13}\)

\(\frac{32}{65}.\left(2x+1\right)^2=\frac{10}{13}\)

\(\left(2x+1\right)^2=\frac{10}{13}\div\frac{32}{65}\)

\(\left(2x+1\right)^2=\frac{25}{16}\)

\(\Rightarrow2x+1\in\left\{\frac{5}{4};-\frac{5}{4}\right\}\)

\(\hept{\begin{cases}2x+1=\frac{5}{4}\\2x+1=-\frac{5}{4}\end{cases}\Rightarrow\hept{\begin{cases}2x=\frac{1}{4}\\2x=-\frac{9}{4}\end{cases}\Rightarrow}\hept{\begin{cases}x=\frac{1}{8}\\x=-\frac{9}{8}\end{cases}}}\)

Vậy \(x\in\left\{\frac{1}{8};-\frac{9}{8}\right\}\)

\(x^3-\frac{9}{16}.x=0\)

\(x\left(x^2-\frac{9}{16}\right)=0\)

\(\hept{\begin{cases}x=0\\x^2-\frac{9}{16}=0\end{cases}\Rightarrow\hept{\begin{cases}x=0\\x^2=\frac{9}{16}\end{cases}\Rightarrow}\hept{\begin{cases}x=0\\x=\pm\frac{3}{4}\end{cases}}}\)

Vậy \(x\in\left\{0;\frac{3}{4};-\frac{3}{4}\right\}\)

a)x+13=32-76

x+13=(-44)

x=-31

b)(-15)+x=43

x=43+15

x=58

c)8-(3-7)

=8+4

=12

d)(-5)-(9-12)

=(-5)+3

=-2

t tôi nha

1)

a) x + 13 = 32 - 76

x + 13 = -44

x = ( -44 ) - 13

x = -57

b) ( -15 ) + x = ( -14 ) - ( -57 )

( -15 ) + x = 43

x = 43 - ( -15 )

x = 58

2)

a) 8 - ( 3 - 7 ) = 8 - ( -4 ) = 12

b) ( -5 ) - ( 9 - 12 ) = ( -5 ) - ( -3 ) = -2

419 bn nha 

= 419^^

         HT