x + ( x + 10 ) + ( x + 20) + (x+ 30 ) + ... + ( x + 100 ) = 770

( x + x + x +... x) + ( 10 + 20 + 30 + ...... + 100) = 770

      X x 11    + 550 = 770

        X x 11 = 770 - 550

           X x 11 = 220 

              x      = 220 : 11

              x = 20

1) 18 . x+x+x=48x25

=18 .x + 2. x=4 . 5. 12 .5

=20.x=20.60

=>x=120:20=60

2) [(2.x-5):(15+10)].20=100

(2x-5):25=20.100

(2x-5):25=2000

2x-5=2000x25

2x-5=50000

2x=50005

x=\(\frac{50005}{2}\)

1) 18.x+x+x=48.25

=> 20x=1200

=> x=60

2) [(2x-5):(15+10)].20=100

=> (2x-5):25 =5

=>2x-5= 125

=>2x=130

=>x=65

a) 3x4-3x-2x+2=x+20   ​​​b) 10+13-(x²- 6x+9)=0

    12-5x=x+20                 -x²+ 6x+14=0... 

    6x=-8

    x=-3/2

a) \(\left(x+1\right)^{x+1}=\left(x+1\right)^{x+5}\)

\(\Leftrightarrow\left(x+1\right)^{x+5}-\left(x+1\right)^{x+1}=0\)(Chuyển vế đổi dấu)

\(\Leftrightarrow\left(x+1\right)^{x+1}\left(\left(x+1\right)^4+1\right)=0\)(Đặt ra ngoài)

\(\Leftrightarrow\orbr{\begin{cases}\left(x+1\right)^{x+1}=0\\\left(x+1\right)^4+1=0\end{cases}}\)(Dấu\(\orbr{\begin{cases}\\\end{cases}}\)là dấu "hoặc" nha bạn)

\(\Leftrightarrow\orbr{\begin{cases}x+1=0\\\left(x+1\right)^4=-1\left(vl\right)\end{cases}}\)(vl là vô lí) (Do (x+1)⁴ >= 0)

\(\Leftrightarrow x=-1\)

Vậy x= -1

b) \(10^x:5^y=20^x\)

\(5^y=10^x:20^x\)

\(5^y=\left(\frac{1}{2}\right)^x\)

Để ý 5 khác 1/2 nên chỉ có x = y = 0 thỏa mãn

Vậy x = y = 0

a) \(\left(x+1\right).10=0\)

                \(x+1=0\)

                \(x=0-1\)

                \(x=-1\)

b) \(15\left(x+2\right)=0\)

            \(x+2=0\)

                    \(x=0-2\)

                    \(x=-2\)

c) \(\left(x-1\right).10=10\)

             \(x-1=10:10\)

              \(x-1=1\)

                 \(x=1+1\)

                  x   =   2

d) \(\left(x-2\right):5=0\)

             \(x-2=0\)

                  \(x=2\)

\(\dfrac{9}{10}\times2+3\times\dfrac{9}{10}+\dfrac{9}{10}:\dfrac{1}{5}\)

\(=\dfrac{9}{10}\times2+\dfrac{9}{10}\times3+\dfrac{9}{10}\times5\)

\(=\dfrac{9}{10}\times\left(2+3+5\right)\)

\(=\dfrac{9}{10}\times10\)

\(=\dfrac{90}{10}\)

\(=9\)

a, đk : x khác 10 \(\Rightarrow x-10=26\Leftrightarrow x=36\left(tm\right)\)

b, đk : x khác 2 

\(\left(x-2\right)^2=100\Leftrightarrow\left[{}\begin{matrix}x-2=10\\x-2=-10\end{matrix}\right.\Leftrightarrow\left[{}\begin{matrix}x=12\\x=-8\end{matrix}\right.\left(tm\right)\)

4,8 : 2 + 16 : 4 + 20 : 10 = 2,4 + 4 + 2 = 8,4

1 000 x 0,06 = 60

4,8 x 0,5 + 16 x 0,25 + 20 : 10

= 4,8 : 2 + 16 : 4 + 20 : 10

= 2,4 + 4 + 2

= 2,4 + 6

= 8,4

1000 x 0,06 = 60

4,8 x 0,5 + 16 x 0,25 + 20 : 10 

= 4,8 : 2 + 16 : 4 + 20 : 10

= 2,4 + 4 + 2

= 8,4