1) 31-3.(x+2) = 7

          3.(x+2) = 31- 7

          3.(x+2)  =  24

              x+2   = 24:3

               x + 2  =  8

               x       = 8-2

              x           = 6

2) 175-25.(2x-1) = 175

            25.(2x-1)  =  175- 175 = 0

                     2x-1  =  0 : 25 = 0

                     2x   = 0 + 1 = 1

                       x    =  1 : 2 = 0,5

3) 25 - x/2 = 19

           x/2  =  25-19

          x/2   =    6

         x : 2   = 6

         x          = 6 x 2 = 12

4) 2.(x-1)+3 = 15

    2.(x-1)        =  15 - 3 = 12

         x - 1        =  12 : 2 = 6

        x               =  6+1 = 7

    (x+1) + (x-2) + (x+3) + (x-4) + ... + (x-50) = -175

 =>x+1 + x-2 + x+3 + x-4 + ... + x-50 = -175

=>(x + x + x + x + ... + x)+(1 - 2 + 3 - 4 + ... - 50) = -175

=>x.50 + (-25) = -175 =>x.50=-150

=>x = -150:50 =-3

câu (1-2+3-4+...-50) bạn tách ra theo quy tắc của tổng đại số rồi tính nhé

Ta có:

    (x+1)+(x-2)+(x+3)+(x-4)+...+(x-50)=-175

⇒ x+1+x-2+x+3+x-4+...+x-50=-175

⇒ 50x+(1+3+5+...+49)–(2+4+6+...+50)=-175

⇒ 50x+625–650=-175

⇒ 50x-25=-175

⇒ 50x=-150

⇒     x=-3

\(\left(x+1\right)+\left(x-2\right)+\left(x+3\right)+\left(x-4\right)...\left(x-50=-175\right)\)

\(\Rightarrow x+1+x-2+x+3+x-4+...+x-50=-175\)

\(\Rightarrow\left(x+x+...+x\right)+\left(1-2+3-4+...-50\right)=-175\)

\(\Rightarrow50x+\left(1-2\right)+\left(3-4\right)+...+\left(49-50\right)=-175\)

\(\Rightarrow50x+\left(-1\right)+\left(-1\right)+...+\left(-1\right)=-175\)

\(\Rightarrow50x+\left(-1\right)50=-175\)

\(\Rightarrow50x+\left(-50\right)=-175\)

\(\Rightarrow50x=-175+50=-125\)

\(\Rightarrow x=-125\div50=\frac{-5}{2}\)

(x+1)+(x-2)+(x+3)+(x-4)+...+(x-50)=-175

x+1+x-2+x+3+x-4+...+x-50=-175

50x+(1-2+3-4+...+49-50)=-175

50x-25=-175

50x=-150

x=-3

\(3.\left[\left(2x-1\right)^2-4\right]-14^2=7^2.5^3:175\)

\(=>3.\left[\left(2x-1\right)^2-4\right]-14^2=35\)

\(=>3.\left[\left(2x-1\right)^2-4\right]=35+14^2=35+196\)

\(=>3.\left[\left(2x-1\right)^2-4\right]=231\)

\(=>\left(2x-1\right)^2-4=231:3\)

\(=>\left(2x-1\right)^2-4=77\)

\(=>\left(2x-1\right)^2=77+4\)

\(=>\left(2x-1\right)^2=81=9^2\)

\(\Rightarrow2x-1=9\)

\(=>2x=9+1\)

\(=>2x=10\)

\(=>x=10:2\)

\(=>x=5\)

Vậy:...

# Wendy Dang

3.[(2x + 1)² - 4] - 14² = 7².5³:175

3.[(2x - 1)² - 4] - 196 = 49.125:175

3.[(2x - 1)² - 4] - 196 = 35

3.[(2x - 1)² - 4] = 35 + 196

3.[(2x - 1)² - 4] = 231

(2x - 1)² - 4 = 231 : 3

(2x - 1)² - 4 = 77

(2x - 1)² = 77 + 4

(2x - 1)² = 81

2x - 1 = 9 hoặc 2x - 1 = -9

*) 2x - 1 = 9

2x = 9 + 1

2x = 10

x = 10 : 2

x = 5 (nhận)

*) 2x - 1 = -9

2x = -9 + 1

2x = -8

x = -8 : 2

x = -4 (loại)

Vậy x = 5

Mọi người giúp mình với

Lời giải:
1. Bạn coi lại đề

2. $=234\times (1257-257)=234\times 1000=234000$

3. $=175\times (1274-273-1)=175\times 1000=175000$

4. $=(4\times 25)\times (125\times 8)=100\times 1000=100000$

1. ...............................

2. $=234\times (1257-257)=234\times 1000=234000$

3. $=175\times (1274-273-1)=175\times 1000=175000$

4. $=(4\times 25)\times (125\times 8)=100\times 1000=100000$

1)

a) \(\left(-175\right)-123+3+175+\left(-3\right)\)

\(=\left[\left(-175\right)+175\right]+\left[3+\left(-3\right)\right]-123\)

\(=0+0-123\)

\(=-123\)

b) \(17.85+15.17-150\)

\(=17.\left(85+15\right)-150\)

\(=17.100-150\)

\(=1700-150\)

\(=1550\)

c) \(176:\left(4.5^2-3.2^2\right)\)

\(=176:\left(4.25-3.4\right)\)

\(=176:\left(100-12\right)\)

\(=176:88\)

\(=2\)

2)

a) \(8-x=-12\)

\(\Rightarrow x=8-\left(-12\right)\)

\(\Rightarrow x=8+12\)

\(\Rightarrow x=20\)

Vậy \(x=20\)

b) \(20+2^3.x=5^2.4\)

\(\Rightarrow20+8.x=25.4\)

\(\Rightarrow20+8.x=100\)

\(\Rightarrow8.x=100-20\)

\(\Rightarrow8.x=80\)

\(\Rightarrow x=80:8\)

\(\Rightarrow x=10\)

Vậy \(x=10\)

c) \(2\left|x-1\right|+5=15\)

\(\Rightarrow2\left|x-1\right|=15-5\)

\(\Rightarrow2\left|x-1\right|=10\)

\(\Rightarrow\left|x-1\right|=10:2\)

\(\Rightarrow\left|x-1\right|=5\)

Xét trường hợp 1: \(x-1=5\)

\(\Rightarrow x=5+1\)

\(\Rightarrow x=6\)

Xét trường hợp 2: \(x-1=-5\)

\(\Rightarrow x=\left(-5\right)+1\)

\(\Rightarrow x=-5+1\)

\(\Rightarrow x=-\left(5-1\right)\)

\(\Rightarrow x=-4\)

Vậy \(x=6\) hoặc \(x=-4\)

Bài 1:

\(a)\left(-175\right)-123+3+175+\left(-3\right)\)

\(=\left[\left(-175\right)+175\right]+\left[\left(-3+3\right)\right]-123\)

\(=0+0-123\)

\(=-123\)

\(b)17.85+15.17-150\)

\(=17.\left(85+15\right)-150\)

\(=17.100-150=1700-150=1550\)

\(c)176:\left(4.5^2-3.2^2\right)\)

\(=176:\left(4.25-3.4\right)\)

\(=176:\left(100-12\right)=176:88=2\)

Bài 2:

\(a)8-x=-12\)

\(\Rightarrow x=8-\left(-12\right)\)

\(\Rightarrow x=20\)

\(b)20+2^3.x=5^2.4\)

\(\Rightarrow20+8.x=25.4\)

\(\Rightarrow20+8.x=100\)

\(\Rightarrow8.x=100-20\)

\(\Rightarrow8.x=80\)

\(\Rightarrow x=80:8=10\)

\(c)2\left|x-1\right|+5=15\)

\(\Rightarrow2\left|x-1\right|=15-5\)

\(\Rightarrow2\left|x-1\right|=10\)

\(\Rightarrow\left|x-1\right|=10:2\)

\(\Rightarrow\left[{}\begin{matrix}x-1=5\\x-1=-5\end{matrix}\right.\Rightarrow\left[{}\begin{matrix}x=6\\x=-4\end{matrix}\right.\)

A = 4 . 2 . 25 . 5 . 175 

A = 2² . 2 . 5² . 5 . 5² . 7 

A = 2²⁺¹ . 5²⁺¹⁺² . 7  

A = 2³ . 5⁵ .7

A = 175000

\(B=4^2-10^4:\left(50\cdot273-50\cdot73\right)\)

\(B=4^2-10^4:\left[50\cdot\left(273-73\right)\right]\)

\(B=4^2-10^4:\left(50\cdot200\right)\)

\(B=4^2-10^4:10^4=4^2-1=15\)

\(C=3\times53\times6+2\times9\times87-18\times40\)

\(C=18\times53+18\times87-18\times40\)

\(C=18\times\left(53+87-40\right)\)

\(C=18\times100=1800\)