Sửa đề :

x + x + 1 + x + 2 + ... + x + 205 = 205

( x + x + ... + x ) + ( 1 + 2 + ... + 205 ) = 205

Số số hạng là : 

( 205 - 1 ) : 1 + 1 = 205 ( số )

Tổng là : 

( 205 + 1 ) . 205 : 2 = 21115

206x + 21115 = 205

206x = -20910

x = -101,5048544

x+(x+1)+(x+2)+....+204+205=205

=>x+(x+1)+(x+2)+....+204=0

mik nghĩ là sai đề bạn ơi

\(x+\left(x+1\right)+\left(x+2\right)+...+\left(x+205\right)=205\)

\(\left(x+x+x+...+x\right)+\left(1+2+3+....+205\right)\)

\(206x+\left[\left(205-1\right):1+1\right].\left(205+1\right):2\)

\(206x+2115=205\)

\(=>...\)

a

=> \(x+2=\dfrac{484}{44}=11\)

=> x = 11 - 2 = 9

b

=> \(x+321=34.12=408\)

=> x = 408 - 321 = 87

c

=> \(x-210=246.15=3690\)

=> x = 3690 + 210 = 3900

d

=> \(205-x=\dfrac{420}{84}=5\)

=> x = 205 - 5 = 200

a: =>x+2=11

=>x=9

b: =>x+321=408

=>x=87

c: =>x-210=3690

=>x=3900

d: =>205-x=5

=>x=200

x : 13 = 205

x = 205 x 13

x = 2665

b) x : 13 = 205

x = 205 x 13

x = 2665

Ta có: 

\(205< 5\times x< 215\)

\(\Rightarrow5\times x=210\)

\(\Rightarrow x=210:5\)

\(\Rightarrow x=42\)

camon ban ạ

205 - 7. ( x + 5 ) = 100 

7 . ( x + 5 ) = 205 - 100 

7 . ( x + 5 ) = 105 

x + 5 = 105 : 7 

x + 5 = 15 

x = 15 - 5 

x = 10 

Vậy x = 10 

Tìm x :

205-7.(x+5)=100

        7.(x+5)=205-100

        7.(x+5)=105

            x+5=105:7

            x+5=15

                x=15-5

                x=10

#Hok_tốt

7. (X+5)=205-100.            7.( x +5)=105.        X+5= 105:7.    x+5=15.    X=10           

1+2+3+...+x=205

\(\frac{x.\left(x+1\right)}{2}=205\)

x.(x+1)=205.2

x.(x+1)=410

x.(x+1)=đề sai