a) x-(-18-x)=x-22

<=> x+18+x=x-22<=> x=-40

b) 18-[19+(-x)]=x-(19+x)+18

<=> 18-19+x=x-19-x+18

<=> x=0

Ta có :

a.x-(-18-x)=x-22

→x+18+x=x-22

→x+x+18=x-22

→2x+18=x-22

→2x-x=-22-18

→x=-40

Vậy x=-40

b. 18-[19+(-x)]=x-(19+x)+18

→18-19+x=x-19-x+18

→-1+x=(x-x)-(19-18)

→-1+x=-1

→x=0

Vậy x=0

tick cho mình na 

a) Ta có: \(\dfrac{x-2}{15}+\dfrac{x-3}{14}+\dfrac{x-4}{13}+\dfrac{x-5}{12}=4\)

\(\Leftrightarrow\dfrac{x-2}{15}-1+\dfrac{x-3}{14}-1+\dfrac{x-4}{13}-1+\dfrac{x-5}{12}-1=0\)

\(\Leftrightarrow\dfrac{x-17}{15}+\dfrac{x-17}{14}+\dfrac{x-17}{13}+\dfrac{x-17}{12}=0\)

\(\Leftrightarrow\left(x-17\right)\left(\dfrac{1}{15}+\dfrac{1}{14}+\dfrac{1}{13}+\dfrac{1}{12}\right)=0\)

mà \(\dfrac{1}{15}+\dfrac{1}{14}+\dfrac{1}{13}+\dfrac{1}{12}>0\)

nên x-17=0

hay x=17

Vậy: x=17

b) Ta có: \(\dfrac{x+1}{19}+\dfrac{x+2}{18}+\dfrac{x+3}{17}+...+\dfrac{x+18}{2}+18=0\)

\(\Leftrightarrow\dfrac{x+1}{19}+1+\dfrac{x+2}{18}+1+\dfrac{x+3}{17}+1+...+\dfrac{x+18}{2}+1=0\)

\(\Leftrightarrow\dfrac{x+20}{19}+\dfrac{x+20}{18}+\dfrac{x+20}{17}+...+\dfrac{x+20}{2}=0\)

\(\Leftrightarrow\left(x+20\right)\left(\dfrac{1}{19}+\dfrac{1}{18}+\dfrac{1}{17}+...+\dfrac{1}{2}\right)=0\)

mà \(\dfrac{1}{19}+\dfrac{1}{18}+\dfrac{1}{17}+...+\dfrac{1}{2}>0\)

nên x+20=0

hay x=-20

Vậy: x=-20

 18 . ( x-16 ) = 18 

x-16 = 18 : 18 

x- 16 = 1

x= 16+1

x= 17 

18 (x - 16) = 18

18 (x - 16) = 18 . 1

Vì 18 = 18 

=> x - 16 = 1

=> x = 17

Vậy x = 17.

    Bài làm :

Ta có :

18 (x - 16) = 18

<=> x - 16 = 1

=> x = 17

Vậy x = 17

a/\(\left(\dfrac{7}{9}\times\dfrac{9}{7}\right)\times\dfrac{25}{28}\)
\(=1\times\dfrac{25}{28}\)
\(=\dfrac{25}{28}\)
b/\(\dfrac{4}{7}\times\dfrac{17}{18}\times\dfrac{7}{4}\times\dfrac{18}{17}\)
\(=\left(\dfrac{4}{7}\times\dfrac{7}{4}\right)\times\left(\dfrac{17}{18}\times\dfrac{18}{17}\right)\)
\(=1\times1\)
\(=1\)

a)

( x - 34 ) . 15 = 0

mà 15 khác 0

=> x - 34 = 0

=> x = 34

b)

18 ( x - 16 ) = 18

=> x - 16 = 1

=> x = 17

Vậy,..........

a,(x-34).15 = 0

=> x-34 = 0

=> x = 34.

b,18.(x-16)=18

=> x- 16 = 1

=> x = 17

hk tốt

\(a)\left(x-34\right).15=0\Leftrightarrow x-34=0\Leftrightarrow x=34\)

\(b)18\left(x-16\right)=18\Leftrightarrow x-16=1\Leftrightarrow x=17\)

\(a.x+\left(x+10\right)+\left(x+14\right)+....+\left(x+162\right)=3434\\ x+\left(x+x+.....+x\right)+\left(10+14+18+.....+162\right)=3434\\ x+x+39+3354=3434\\ x\cdot40=80\\ x=2\)

a.x+(x+10)+(x+14)+....+(x+162)=3434

x+(x+x+.....+x)+(10+14+18+.....+162)=3434

x+x.39+3354=3434

x⋅40=80

x=2

x+(x+10)+(x+14)+(x+18) + ...+(x+162) = 3434

Số số hạng của dãy số 10, 14, 18,..,162

(162 - 10) : 4 + 1 = 39 

VT = x  + 39.x + (10 + 162) x 39 : 2  = 3434

40x + 172 x 39 :2 =3434

40x + 6708 : 2 = 3434 

40x + 3354 = 3434

40x             = 3434 - 3354 

40x             = 80

x= 80 : 40

x= 2

a)   (x-34)x15=0

x-34=0 x15

x-34=0

x=34+0(tìm số bị trừ)

x=34

b)     18x(x-16)=18

(x-16)=18:18

x-16=1

x=1+16(tìm số bị trừ)

x=17

a) x-34=0/15=0

x=0+34=34

b) x-16=18/18=1

x=1+16=17

( x - 34 ) x 15 = 0

( x - 34 ) = 0 x 15

( x - 34 )  = 0

X = 0 + 34 = 34

x = 34

18 x ( x - 16 ) = 18

( x - 16 ) = 18 : 18

( x - 16 ) = 1

x = 16 + 1

x = 17