ko chép lại đề bài

<=> {(-3x+4x)+2[ 45-(x+2x)-9x-21]}=55

<=> {x+2[(45-21)-(3x+9x)]}=55

<=> x+2[24-12x]=55

<=> x+48-24x=55

<=> 48-23x=55

<=>23x=48-55=-7

<=>x=\(\frac{-7}{23}\)

mong các bn giúp mik, mik đag cần gấp 

{-3x + 2. [ 45 - x - 9x -21 - 2x ] + 4x } = 55

suy ra { - 3x +2.[24 - 12x] + 4x } = 55

suy ra x+ 48 - 24x = 55

suy ra - 23x=7

suy ra x= - 7/23

x=103/23

-[-3x+2(45-x-9x+21-2x)+4x=55       

-[-3x+2(24-12x)+4x]=55

-(-3x+48-24x+4x)=55

-(48-23x)=55

23x=55+48

x=103/23

Xem lại dùm mink nha

\(\left\{-3x+2\left[45-x-3\left(3x+7\right)-2x\right]+4x\right\}=55-103\)

\(\left\{-3x+2\left[45-x-9x-21-2x\right]+4x\right\}=-48\)

\(-3x+90-2x-18x-42-4x+4x=-48\)

\(-3x-2x-18x-4x+4x=-48-90+42\)

\(-23x=-96\Leftrightarrow x=\frac{96}{23}\)

đag rảnh nên ... lm nốt 

\(-57:\left[-2\left(2x+1\right)^2-\left(-9\right)^0\right]=-106\)

\(-2\left(2x+1\right)^2+1=57\)

\(-2\left(2x+1\right)^2=56\)

\(\left(2x+1\right)^2=-28\)

\(\Rightarrow\orbr{\begin{cases}2x+1=-2\sqrt{7}\\2x+1=2\sqrt{7}\end{cases}\Rightarrow\orbr{\begin{cases}2x=-1-2\sqrt{7}\\2x=-1+2\sqrt{7}\end{cases}}}\)

\(\Rightarrow\orbr{\begin{cases}x=\frac{-1-2\sqrt{7}}{2}\\x=\frac{-1+2\sqrt{7}}{2}\end{cases}}\)