a) 72.5–(2x+1)=630:972.5–(2x+1)=630:9

⇒245–2x–1=70⇒245–2x–1=70

⇒−2x=−22+70⇒−2x=−22+70

⇒−2x=−174⇒−2x=−174

⇒x=87⇒x=87

b)(10−4x)+120:23=17

10−4x+15=17

10−4x=17−15

10−4x=2

4x=10−2

4x=8

x=8:4

x=2

 

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,<=> 145-2x-1=70

<=> 2x=74

<=> x=37

b, <=> 10-4x+15=17

<=> 4x=8

<=> x=2

\(7^2\cdot5-\left(2x+1\right)=630\div9\)

\(49\cdot5-\left(2x+1\right)=70\)

     \(245-\left(2x+1\right)=70\)

                     \(2x+1=245-70\)

                      \(2x+1=175\)

                        \(2x=175-1\)

                         \(2x=174\)

                            \(x=174\div2\)

                             \(x=87\)

\(\left(10-4x\right)+120\div2^3=17\)

  \(\left(10-4x\right)+120\div8=17\)

\(\left(10-4x\right)+15=17\)

    \(10-4x=17-15\)

      \(10-4x=2\)

                 \(4x=10-2\)

                  \(4x=8\)

                      \(x=8\div4\)

                      \(x=2\)

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

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

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

                 \(2x+1=245-70\)

                  \(2x+1=175\)

                   \(2x=175-1\)

                   \(2x=174\)

                   \(x=174:2\)

                   \(x=87\)

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

ok fine

Bn có bt đọc chữ ko

Giúp mình nhanh với ạ! Thank,s

a) `1/4 x + 7/4 x = -6`

`=> x(1/4 + 7/4) = -6`

`=> x. 2 = -6`

`=> x= -6/2`

`=> x= -3`

Vậy `x= -3`

b) `1/4 x +2x = 9/2`

`=> x(1/4 +2) =9/2`

`=> x(1/4 + 8/4) = 9/2`

`=>x. 9/4 =9/2`

`=> x= 9/2 : 9/4`

`=> x= 2`

Vậy `x=2`

a) 52x - 3 - 2 . 52 = 52 . 3

x - 3/52 - 2 = 3

x = 3 + 2 + 3/52

x = 263/52

b) 740 / (x + 10) = 102 - 2 . 13

740 / (x + 10) = 76

x + 10 = 740 / 76

x + 10 = 185/19

x = 185/19 - 10

x = -5/19

c) 65 - 4x + 2 = 20140

65 - 4x = 20140 - 2

65 - 4x = 20138

4x = 65 - 20138

4x = -20073

x = -20073/4

d) 120 + 2 . (3x - 17) = 214

60 + 3 . x - 17 = 107

20 + x - 17/3 = 107/3

20 + x = 107/3 + 17/3

20 + x = 124/3

x = 124/3 - 20

x = 64/3

e) 41 - 2x + 1 = 9

42 - 2x = 9

21 - x = 9/2

x = 21 - 9/2

x = 33/2

a) <=> (4x - 4x + 5)(4x + 4x - 5) = 15 <=> 40x = 15 <=> x = 3/8

a) <=> (4x - 4x + 5)(4x + 4x - 5) = 15 <=> 5(8x-5) = 15

<=> 40x = 40 <=> x = 1

Cái này mới chuẩn

b) (2x+1)(1-2x)+(1-2x)²=18 <=> 1 - 4x² + 4x² - 4x + 1 = 18

<=> -4x = 16 <=> x = -4