x - [( x - 7 ) + (x - 14 + 8 )] = 2x - 14

 x - [ x - 7 + x - 14 + 8 ] = 2x - 14

 x -  x + 7 - x + 14 - 8  = 2x - 14

x - x - x - 2x = -14 - 7 - 14 + 8

-3x = -27

=> x = 9

Vậy...

Chúc em học tốt!!!

x = 9 

#Pikachu:))#

x-[(x-7)+(x-14+8)]=2x-14

x-[x-7+x-14+8]=2x-14

x-x+7-x+14-8=2x-14

x-x-x-2x=-14-7-14+8

-3x=-27

=> x=9

Vậy x=9

a) x + 4 = – 14 – 9

x + 4 = – 23

x = – 23 – 4

x = – 27

b) 3x = – 14 + 2

3x = – 12

x = – 12 : 3

x = – 4

c) 2| x | = 4 – (– 8)

2| x | = 12

| x | = 6

x = 6 hoặc x = – 6

d) |x – 2| = 7

x – 2 = 7 hoặc x – 2 = – 7

x = 9 hoặc x = – 5

a.\(\left(-12\right)x-14=-2\)

\(\left(-12\right)x=-2+14\)

\(\left(-12\right)x=12\)

\(x=12:\left(-12\right)\)

\(x=-1\)

\(b,\left(-8\right)x=\left(-5\right)\left(-7\right)-3\)

\(\left(-8\right)x=35-3\)

\(\left(-8\right)x=32\)

\(x=32:\left(-8\right)\)

\(x=-4\)

\(c,\left(-9\right)x+3=\left(-2\right)\left(-7\right)+16\)

\(\left(-9\right)x+3=14+16\)

\(\left(-9\right)x+3=30\)

\(\left(-9\right)x=30-3\)

\(\left(-9\right)x=27\)

\(x=27:\left(-9\right)\)

\(x=-3\)

Bài 1:

a. $(-20)+x=-30$

$x-20=-30$

$x=-30+20=-(30-20)=-10$

b.

$(-10)-x=-20$

$x=(-10)-(-20)=-10+20=20-10=10$

c. Đề sai. Bạn xem lại.

d.

$x+(-3)=-7$

$x=-7-(-3)=-7+3=-(7-3)=-4$

e.

$x-(-5)=-9$

$x=(-9)+(-5)=-14$

f.

$x(-11)=12$

$x=\frac{12}{-11}=\frac{-12}{11}$

h.

$2x-10=20$

$2x=20+10=30$

$x=30:2=15$

l.

$4x-8=-8$
$4x=-8+8=0$

$x=0:4=0$

k.

$-12-(-2)x=-8$

$(-2)x=-12-(-8)=-12+8=-(12-8)=-4$

$x=(-4):(-2)=2$

Bài 2:

a. $-20-(10-x)=-3$

$10-x=-20-(-3)=-20+3=-(20-3)=-17$

$x=10-(-17)=10+17=27$

b.

$14+(14-x)=-2$
$14-x=-2-14=-16$

$x=14-(-16)=14+16=30$

c.

$-15-(x-3)=-7$

$x-3=-15-(-7)=-15+7=-8$

x=-8+3=-5$

d.

$(x+4)+(-20)=-8$

$x+4=-8-(-20)=-8+20=12$
$x=12-4=8$

e.

$-2x-2=-4$

$-2x=-4+2=-2$

$x=(-2):(-2)=1$

f.

$-2x+4=-4$

$-2x=-4-4=-8$

$x=(-8):(-2)=4$

l.

$-12-(-2)x=-2-4=-6$

$(-2)x=-12-(-6)=-12+6=-6$

$x=(-6):(-2)=3$

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

Ai giải hộ e với e phải đi học

a. 8 + (x - 9) = 125 - 64

8 + (x - 9) = 61

x - 9 = 53

x = 62

b. 5 x (X + 7) - 10 = 8 x 5

5 x (X + 7) - 10 = 40

5 x (X + 7) = 50

X + 7 = 10

X = 3

a,\(\left(\frac{7}{5}-2x\right).\frac{40}{20}=\frac{8}{14}\)

\(\Rightarrow\left(\frac{7}{5}-2x\right).2=\frac{4}{7}\)

\(\Rightarrow\frac{7}{5}-2x=\frac{4}{7}:2\)

\(\Rightarrow\frac{7}{5}-2x=\frac{2}{7}\)

\(\Rightarrow2x=\frac{7}{5}-\frac{2}{7}\)

\(\Rightarrow2x=\frac{39}{35}\)

\(\Rightarrow x=\frac{39}{35}:2\)

\(\Rightarrow x=\frac{39}{70}\)

b, \(\frac{7}{2}.x-20\%.x=-4\)

\(\Rightarrow x\left(\frac{7}{2}-20\%\right)=-4\)

\(\Rightarrow x\left(\frac{7}{2}-\frac{1}{5}\right)=-4\)

\(\Rightarrow x\frac{7}{10}=-4\)

\(\Rightarrow x=-4:\frac{7}{10}\)

\(\Rightarrow x=-\frac{40}{7}\)

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

c) (-8).x = (-7).(-6) - 2

-8.x = 42 - 2

-8x = 40

x = 40 : (-8)

x = -5

a) (X+7)x8-14=66                                       b) Xx7+Xx12=266

(X+7)x8        = 66+14                                      Xx(7+12)=266

(X+7)x8        = 80                                            Xx19    =266

X+7              = 80 : 8                                       X          = 266 : 19

X +7               = 10                                         X            = 14

X                   = 10-7

X                    = 3

k mik nha

a,(x+7)*8-14=66                            b,x*7+x*12=266

(x+7)*8=66+14=80                            x*(7+12)=266

x+7=80:8=10                                    x*19=266

x=10-7=3                                             x=266:19

                                                           x=14

tk mk nha bn

chúc bn hk giỏi

a, (X+7)x8-14=66

=>(X+7)x8=66+14

=>(X+7)x8=80

=>X+7=80:8

=>X+7=10

=>X=10-7

=>X=3 

câu b tương tự