1, -15 + \(x\) = -14 - (-57)

   -15 + \(x\)  = -14 + 57

             \(x\) = -14 + 57  + 15

             \(x\) = 43 + 15

             \(x\) = 58

2, (-14) + \(x\) - 7 = -10

    -14 + \(x\) - 7 = -10

     - 21 + \(x\)    = - 10

                \(x\)   = -10 + 21

                 \(x\) = 11

3, - \(x\) - 14 + 32  = -26

    - \(x\) + 18          = - 26

      \(x\)                  = 18 + 26

      \(x\)                  = 44 

X+\(\dfrac{2}{7}\)=\(\dfrac{1}{2}\)

X     = \(\dfrac{1}{2}\)-\(\dfrac{2}{7}\)
X     = \(\dfrac{3}{14}\)
Chọn đáp án A. \(\dfrac{3}{14}\)

A

a: \(A=\left|3x-9\right|+1.5\ge1.5\forall x\)

Dấu '=' xảy ra khi x=3

b: \(B=\left|x-7\right|-14\ge-14\forall x\)

Dấu '=' xảy ra khi x=7

a, Ta có \(A=\left|3x-9\right|+1,5\)

Ta thấy: \(\left|3x-9\right|\ge0\Rightarrow\left|3x-9\right|+1,5\ge1,5\Rightarrow A\ge1,5\)

Dấy"=" xảy ra \(\Leftrightarrow3x-9=0\Leftrightarrow3x=9\Leftrightarrow x=3\)

Vậy \(A_{min}=1,5\Leftrightarrow x=0\)

b, Ta có \(B=\left|x-7\right|-14\)

Ta thấy: \(\left|x-7\right|\ge0\Rightarrow\left|x-7\right|-14\ge-14\Rightarrow B\ge-14\)

Dấu "=" xảy ra \(\Leftrightarrow x-7=0\Leftrightarrow x=7\)

Vậy \(B_{min}=-14\Leftrightarrow x=7\)

c, Ta có: \(C=-\left|\dfrac{1}{2}x-4\right|+13\Rightarrow C=13-\left|\dfrac{1}{2}x-4\right|\)

Ta thấy: \(\left|\dfrac{1}{2}x-4\right|\ge0\Rightarrow13-\left|\dfrac{1}{2}x-4\right|\le13\Rightarrow C\le13\)

Dấu "=" xảy ra \(\Leftrightarrow\dfrac{1}{2}x-4=0\Leftrightarrow\dfrac{1}{2}x=4\Leftrightarrow x=8\)

Vậy \(C_{max}=13\Leftrightarrow x=8\)

d, Ta có: \(D=-\left|1,5-x\right|-14\Rightarrow D=-14-\left|1,5-x\right|\)

Ta thấy: \(\left|1,5-x\right|\ge0\Rightarrow-14-\left|1,5-x\right|\le-14\Rightarrow D\le-14\)

Dấu "=" xảy ra\(\Leftrightarrow1,5-x=0\Rightarrow x=1,5\)

Vậy \(D_{max}=-14\Leftrightarrow x=1,5\)

Hoctot

5 + ( x + 27 ) = 64

a) \(\Rightarrow x+27=59\Rightarrow x=32\)

b) \(\Rightarrow x-2=39\Rightarrow x=41\)

c) \(\Rightarrow x+5=-322\Rightarrow x=-327\)

d) \(\Rightarrow5x=35\Rightarrow x=7\)

e) \(\Rightarrow4\left(x-5\right)=56\Rightarrow x-5=14\Rightarrow x=19\)

f) \(\Rightarrow15+x=37\Rightarrow x=22\)

g) \(\Rightarrow7\left(13-x\right)=35\Rightarrow13-x=5\Rightarrow x=8\)

h) \(\Rightarrow10\left(x+1\right)=100\Rightarrow x+1=10\Rightarrow x=9\)

\(x:\dfrac{3}{4}\) = \(\dfrac{9}{14}-\dfrac{1}{7}\)

\(x:\dfrac{3}{4}\) = \(\dfrac{1}{2}\)

\(x=\dfrac{1}{2}\) x \(\dfrac{3}{4}\)

\(x=\dfrac{3}{8}\)

\(x\)x \(\dfrac{1}{2}-\dfrac{1}{4}\)=\(\dfrac{2}{3}\)

\(x\) x \(\dfrac{1}{4}\)     =\(\dfrac{2}{3}\)

\(x\)            = \(\dfrac{2}{3}:\dfrac{1}{4}\)

\(x\)             \(\dfrac{8}{3}\)

5/6

5/6 nhé 

a) \(x-\dfrac{5}{8}=\dfrac{1}{4}\)

\(\Rightarrow x=\dfrac{1}{4}+\dfrac{5}{8}\)

\(\Rightarrow x=\dfrac{2}{8}+\dfrac{5}{8}=\dfrac{7}{8}\)

b) \(\dfrac{4}{7}:x=-\dfrac{5}{14}\)

\(\Rightarrow x=\dfrac{4}{7}:-\dfrac{5}{14}\)

\(\Rightarrow x=-\dfrac{8}{5}\)

a) \(x-\dfrac{5}{8}=\dfrac{1}{4}\)

\(x=\dfrac{1}{4}+\dfrac{5}{8}=\dfrac{2}{8}+\dfrac{5}{8}\)

\(x=\dfrac{7}{8}\)

b) \(\dfrac{4}{7}:x=-\dfrac{5}{14}\)

\(x=\dfrac{4}{7}:\left(-\dfrac{5}{14}\right)=\dfrac{4}{7}.\left(-\dfrac{14}{5}\right)\)

\(x=-\dfrac{8}{5}\)

a] x-5/8=1/4

    x       = 1/4 + 5/8

    X       = 7/8

B] 4/7:x= -5/14

          x= 4/7 : -5/14

          x= -8/5

a:  =>x-16=74

nên x=90

12 x (5-x) -7 x (x-5) =14

12 x (5-x) +7 x (5-x) =14

(5-x ) x (12+7)         =14

(5-x) x19                 =14

5-x                         =14 :19=14/19

x                           =5 - 14/19 =81/19