a/\(x:27=3,6\)
\(\Rightarrow x=97,2\)
b/\(\dfrac{2x+1}{-27}=\dfrac{-3}{2x+1}\)
\(\Rightarrow\left(2x+1\right)^2=81\)
\(\Rightarrow\left[{}\begin{matrix}2x+1=9\\2x+1=-9\end{matrix}\right.\)
\(\Rightarrow\left[{}\begin{matrix}2x=8\\2x=-10\end{matrix}\right.\)
\(\Rightarrow\left[{}\begin{matrix}x=4\\x=-5\end{matrix}\right.\)
Vậy \(x\in\left\{4;-5\right\}\)

a) x=3,6\(\times\) 27=97,2

a,x:27=3,6

x=3,6:27

x\(\approx\)0,13

\(\Rightarrow\)x=0,1(3)

a) \(3\left(2x-5\right)+125=134\)

\(\Leftrightarrow3\left(2x-5\right)=9\)

\(\Leftrightarrow2x-5=3\)

\(\Leftrightarrow2x=8\Leftrightarrow x=4\)

b) \(\left(2x+5\right)+\left(2x+3\right)+\left(2x+1\right)=27\)

\(\Leftrightarrow6x+9=27\)

\(\Leftrightarrow6x=18\Leftrightarrow x=3\)

d) \(27\left(x-27\right)-27=0\)

\(\Leftrightarrow27\left(x-27\right)=27\)

\(\Leftrightarrow x-27=1\Leftrightarrow x=28\)

3.(x+5)-2x=27
3.x+3.5-2x=27
3x+15-2x=27
x.(3-2)+15=27
x.  1    +15=27
  x       +15=27
  x             =27-15
  x             =12

Lời giải:

a.

$x:27=-2:3,6=\frac{-5}{9}$

$x=27.\frac{-5}{9}=-15$

b.

$\frac{2x+1}{-27}=\frac{-3}{2x+1}$

$\Rightarrow (2x+1)^2=(-27)(-3)=81=9^2=(-9)^2$

$\Rightarrow 2x+1=9$ hoặc $2x+1=-9$

$\Rightarrow x=4$ hoặc $x=-5$

ĐKXĐ: \(-\frac{5}{2}\le x\le2\)

Ta có \(VT=27\left(\sqrt{5+2x}+\sqrt{4-2x}\right)\ge27\sqrt{5+2x+4-2x}=81\)

Xét vế phải với hàm \(f\left(x\right)=\left(4x+1\right)^2\) trên \(\left[-\frac{5}{2};2\right]\)

\(f\left(-\frac{1}{4}\right)=0\) ; \(f\left(-\frac{5}{2}\right)=81\) ; \(f\left(2\right)=81\)

\(\Rightarrow0\le f\left(x\right)\le81\Rightarrow VP\le81\)

\(\Rightarrow VT\ge VP\) \(\forall x\in\left[-\frac{5}{2};2\right]\)

Vậy nghiệm của BPT là \(-\frac{5}{2}\le x\le2\)

( 2x - 27 ) + 17 = x - 27

2x - 27 + 17 = x - 27

2x - x = 27 - 27 + 17

x = 17

=> 2x-27+17 = x-27

=> 2x-10 = x-27

=> 2x-10+27 = x

=> 2x+17 = x

=> x-2x = 17

=> -x = 17

=> x=-17

Vậy x=-17

Tk mk nha

( 2x - 27 ) + 17 = x - 27

2x - 27 + 17 = x - 17

2x - x = -17 - 17 + 27

x = -34 + 27

x = -7

9-(27-2x)=-|-27|-15

9-(27-2x)=-42

27-2x = 51

2x = 27 - 51

2x = -24

x = -24 : 2

x = -12