Tìm x biết

\(5+x=10\)

\(\Leftrightarrow x=10-5\)

\(\Leftrightarrow x=5\)

Vậy x = 5

\(10+x=12\)

\(\Leftrightarrow x=12-10\)

\(\Leftrightarrow x=2\)

Vậy x = 2

5+x=10

    x=10-5

    x=5

10+x=12

      x=12-10

       x=2

a. 5+x=10

        x=10-5

        x=5

b. 10+x=12

          x=12-10

          x=2

`5x - 20 - x - 2 = 2x - 6`

`<=> 4x - 22  = 2x - 6`

`<=> 2x = 16`

`<=>x=8`

=>5x-20-x-2=2x-6

=>4x-22=2x-6

=>2x=16

=>x=8

5^x+1 . 10 = 1250

=> 5^x+1 = 1250 : 10 = 125

=> 5^x+1 = 5³

=> x + 1 = 3

=> x = 3 - 1 = 2

\(5^{x+1}.10=1250\)

\(\Rightarrow5^{x+1}=1250:10\)

\(\Rightarrow5^{x+1}=125\)

\(\Rightarrow5^{x+1}=5^3\)

\(\Rightarrow x+1=3\)

\(\Rightarrow x=3-1\)

\(\Rightarrow x=2\)

5^x+1=1250:10

5^x+1=125

5^x+1=5^3

=>x+1=3

     x    =3-1

 vậy x =2

BT1 :thực hành phép tính

4/3+-11/31+3/10-20/31-2/5 = 7/30

7/12-1/-16+3/4 = 67/48

2/11.-5/4+-9/11.5/4+ 1 và 3/4 = -1/4 * và 3/4 là sao bạn *

-9/27-25/75 = -2/3

Bài 2:

a: 5/7-3/7x=1

=>3/7x=-2/7

hay x=-2/3

b: \(x+\dfrac{2}{3}=\dfrac{-1}{12}\cdot\dfrac{-4}{5}=\dfrac{1}{15}\)

=>x=1/15-2/3=-9/15=-3/5

c: \(x-4=\dfrac{-14}{35}:\dfrac{7}{5}=\dfrac{-14}{35}\cdot\dfrac{5}{7}=\dfrac{-70}{245}=\dfrac{-2}{7}\)

=>x=4-2/7=26/7

\(5\le5^x\le625\)

\(\Rightarrow5^1\le5^x\le5^4\)

\(\Rightarrow1\le x\le4\)

\(\Rightarrow x\in\left\{1;2;3;4\right\}\)

\(5\le5^x\le5^4\)

\(=>x\in\left\{1;2;3;4\right\}\)

\(5\le5^x\le5^4\\ \Rightarrow x\in\left\{1;2;3;4\right\}\)

x + x : 1/5 + x : 1/8 - x × 4 = 1250

x + x × 5 + x × 8 - 4 × x = 1250

x × (1 + 5 + 8 - 4) = 1250

x × 10 = 1250

x = 1250 : 10

x = 125