ngoặc vuông ở đâu

[124 - (20 - 4x)] : 30 + 7 = 11

=> [124 - (20 - 4x)] : 30 = 4

=> 124 - 20 + 4x = 120

=> 104 + 4x = 120

=> 4x = 16

=> x = 4

[124-(20+4x)]:30+7=11

[124-(20+4x)]:30 = 11-7

[124-(20+4x)]:30 = 4

[124-(20+4x)] =4 x 30

[124-(20+4x)] =120

[124-20-4x] =120

104-4x = 120

  -4x  = 120-104

  -4x  = 16

  x  = -4

20 + 4 x ? hả cậu ?

124-20-4x:30+7=11

104-120x+7=11

-120x=11-104-7

-120x=-100

x=5/6

~Tk mình nha!!!>.<~

a. 4(2x+7)-3(3x-2)=24

 => 8x+28-9x+6=24

=> -x+34=24

=> -x=-10=> x=10

b. 2(x-1)+3(x-2)=x-4

=> 2x-2+3x-6=x-4

=> 5x-8=x-4

=> 5x-x=-4+8

=> 4x=4=> x=1

c. [124-(20-4x)]:30+7=11

=> (124-20+4x):30=4

=> (104+4x):30=4

=> 104+4x=120

=> 4x=96 => x=24

uytu tyuyt

[124-(20-4x)]:30+7=11

=>(124-20-4x):30=4

=>(104-4x):30=4

phải là :30=4 chứ bạn chép sai đề ak?

=>104+4x=120

=>4x= 120-104

=>4x=16

=>x=16:4

=>x=4

(mk sửa lại nhé nếu đúng đề)

~ chúc bạn học tốt~

\(a\)\(.\)\(7^2.5-\left(2x+1\right)=630:9\)

\(49.5-\left(2x+1\right)=70\)

\(245-\left(2x+1\right)=70\)

                 \(2x+1=245-70\)

                  \(2x+1=175\)

                   \(2x=175-1\)

                   \(2x=174\)

                   \(x=174:2\)

                   \(x=87\)

Vậy \(x=87\)

\(b.\)\(\left(10-4x\right)+120:2^3=17\)

        \(\left(10-4x\right)+120:8=17\)

         \(\left(10-4x\right)+15=17\)

          \(10-4x=17-15\)

           \(10-4x=2\)

           \(4x=10-2\)

            \(4x=8\)

            \(x=8:4\)

            \(x=2\)

Vậy \(x=2\)

\(c.\)\(\left[124-\left(20-4x\right)\right]:30+7=11\)

\(\left[124-\left(20-4x\right)\right]:30=11-7\)

\(\left[124-\left(20-4x\right)\right]:30=4\)

\(\left[124-\left(20-4x\right)\right]=4.30\)

\(\left[124-\left(20-4x\right)\right]=120\)

\(124-20+4x=120\)

\(104+4x=120\)

\(4x=120-104\)

\(4x=16\)

\(x=16:4\)

\(x=4\)

Vậy \(x=4\)

\(d.\)\(\left|2x+5\right|=1\)

\(\Rightarrow2x+5\in\left\{-1;1\right\}\)

\(\Rightarrow2x\in\left\{-6;-4\right\}\)

\(\Rightarrow x\in\left\{-3;-2\right\}\)

Vậy \(x\in\left\{-3;-2\right\}\)

học tốt

a) \(7^2\cdot5-\left(2x+1\right)=630:9\)

\(\Leftrightarrow49\cdot5-2x-1=70\)

\(\Leftrightarrow244-2x=70\)

\(\Leftrightarrow2x=244-70\)

\(\Leftrightarrow2x=174\)

\(\Leftrightarrow x=87\)

Vậy x=87.

b) \(\left(10-4x\right)+120:2^3=17\)

\(\Leftrightarrow10-4x+120:8=17\)

\(\Leftrightarrow10-4x+15=17\)

\(\Leftrightarrow25-4x=17\)

\(\Leftrightarrow4x=25-17=8\)

\(\Leftrightarrow x=2\)

Vậy x=2

c)\([124-\left(20-4x\right)]:30+7=11\)

\(\Leftrightarrow\left(124-20+4x\right):30=4\)

\(\Leftrightarrow104+4x=120\)

\(\Leftrightarrow4x=120-104=16\)

\(\Leftrightarrow x=4\)

Vậy x=4

d) \(|2x-5|=1\)

\(\Leftrightarrow\orbr{\begin{cases}2x-5=1\\2x-5=-1\end{cases}}\)

\(\Leftrightarrow\orbr{\begin{cases}2x=6\\2x=4\end{cases}}\)

\(\Leftrightarrow\orbr{\begin{cases}x=3\\x=2\end{cases}}\)

Vậy \(x\in\text{ }\left\{3;2\right\}\)

Sorry mình ghi nhầm đề bài phần d

a) 72,5 - (2x + 1) = 630 : 9

⇒ 72,5 - (2x + 1) = 70

⇒ 2x + 1 = 2,5

⇒ 2x = 1,5

⇒ x = 0,75

b) (10 - 4x) + 120 : 2³ = 17

⇒ (10 - 4x) + 120 : 8 = 17

⇒ (10 - 4x) + 15 = 17

⇒ 10 - 4x = 2

⇒ 4x = 8

⇒ x = 2

Vậy x = 2

c) [124 - (20 - 4x)] : 30 + 7 = 11

⇒ [124 - (20 - 4x)] : 30 = 4

⇒ 124 - (20 - 4x) = 120

⇒ 20 - 4x = 4

⇒ 4x = 16

⇒ x = 4

Vậy x = 4

a ) \(\frac{2}{3}-x=\frac{5}{4}\)

\(\Rightarrow x=\frac{2}{3}-\frac{5}{4}=\frac{-7}{12}\)

Vậy x= \(\frac{-7}{12}\)

Căng quá 

\(a,\frac{2}{3}-x=\frac{5}{4}\)

\(\Rightarrow x=\frac{2}{3}-\frac{5}{4}\)

\(\Rightarrow x=-\frac{7}{12}\)

\(b,\left[124-\left(20-4x\right)\right]:30+7=11\)

\(\Rightarrow\left[124-20+4x\right]:30=11-7\)

\(\Rightarrow\left[104+4x\right]:30=4\)

\(\Rightarrow104+4x=120\)

\(\Rightarrow4x=120-104=16\)

\(\Rightarrow x=16:4\)

\(\Rightarrow x=4\)

~Study well~

#ARMY_BLINK#

\(a,\left|2x-5\right|=1\)

\(\Rightarrow\orbr{\begin{cases}2x-5=1\\2x-5=-1\end{cases}\Rightarrow\orbr{\begin{cases}2x=6\\2x=4\end{cases}\Rightarrow}\orbr{\begin{cases}x=3\\x=2\end{cases}}}\)

b, đề thiếu 

À ý b, thiếu : [124-920-4x)]:30+7=11 như này là đề đúng

bn sửa hình như sai sai 

\(\left[124-\left(20-4x\right)\right]:30+7=11\)

\(\left[124-20+4x\right]:30=4\)

\(124-20+4x=120\)

\(104+4x=120\)

\(4x=16\)

\(x=4\)