a , x = 501

b , x = 1999

a) 5 * x - 1952 = 2500 - 1947

    5 * x -1952 =553

    5 * x             = 553 + 1952

    5 * x             =2505

    x                   = 501

b)x * 1999 - x = 1999*1997 +1999

 x * ( 1999 -1) = 1999*(1997 +1)

 x * 1998          =1999 * 1998

x                        =1999

7x-2x-1952=2500-1947

=> 5x-1952=553

=> 5x =553+1952

=> 5x=2505

=>   x =2505:5

=>   x =501

x = 501         

a)15.x+15.2,7=105

15.(x+2,7)=105

x+2,7=7

x=7-2,7

x=4,3

Vậy x=4,3

b)x:7=920699:70

x:7=920699:10:7

x:7=92069,9:7

x=92069,9

Vậy x=92069,9

c)5.x-1952=2500-1947

  5.x-1952=553

 5.x=2505

 x=501

Vậy x=501

d)x.2016-x=2016.2017+2016

  x.(2016-1)=2016.(2017+1)

 x.2015=2016.2018

x=\(\frac{2016.2018}{2015}\)

Vậy x\(\frac{2016.2018}{2015}\)

15.x+15.2,7=105
<=> 15.( x + 2,7 ) = 105 
=> x + 2,7 = 7
=> x = 7 - 2,7 
=> x = 4,3

x:7=920699:70
<=> x . 70 = 920699 . 7 
=> x . 70 = 6444893
=> x = 6444893 : 70 
=> x = 92069,9

5.x-1952=2500-1947
=> 5x - 1952 = 553
=> 5x = 553 + 1952 
=> 5x = 2505 
=> x = 2505 : 5 
=> x = 501 

x.2016-x=2016.2017+2016
=> x ( 2016 - 1 ) = 2016 ( 2017 + 1) 
=> x . 2015 = 2016 . 2018 
=> x : 2018 = 2016 : 2015 
=> x : 2018 = \(\frac{2016}{2015}\)
=> x = \(\frac{2016}{2015}.2018\approx2019\)

a) 210 : x = 14,92 - 6,52

    210 : x = 8,4

             x = 210 : 8,4

             x = 25

Vậy x = 25

a, 210 : x = 8,4

             x = 210 : 8,4

             x = 25

b, 5 x X - 1952 = 2500 - 1947

5 x X - 1952 = 553

5 x X = 553 + 1952

5 x X = 2505

      X = 2505 : 5

      X = 501

c, X x 1999 - x = 1999 x 1997b + 1999

X x 1998 = 1999 x 1997b + 1999

Mình hơi bí câu này, thông cảm

5 x y -1952 =553

5 x y            = 553 + 1952

5 x y            = 2505

     y             = 2505 : 5

     y             = 501

y x 2011 - y = 2011 x 2009 + 2011 x 1

y x 2011 - y x 1 =2011 x 2009 + 2011x1

y x ( 2011 - 1) =   2011 x ( 2009 +1)

y x 2010         =   2011 x  2010

nhìn vào phép tính trên ta thấy cả 2 vế đều có 1 thừa số chung đó là 2010 

  mà 2 vế bằng nhau

 nên y = 2011

bn nào đi qua thấy đúng cho mk 1 k nha. yêu mọi người moa

1

a)

5 x X - 1952 = 2500 - 1947

5 x X - 1952 = 553

5 x X            = 553 + 1952

5 x X            = 2505

      X            = 2505 : 5

      X            = 501

b)

X x 2011 - X       = 2011 x 2009 + 2011

X x 2011 - X x 1 = 2011 x 2009 + 2011 x 1

X x ( 2011 + 1 )  = 2011 x ( 2009 + 1 )

X x 2012            = 2011 x 2010

X x 2012            = 4042110 

X                        = 4042110 : 2012

X                        = \(_{\frac{2021055_{ }}{1006}}\)

a) \(\frac{y}{6}=\frac{2010}{15}\)                              c)  \(x-\frac{1}{3}=\frac{1}{4}\)             e)\(5y-1952=2500-1947\)

\(y=\frac{2010}{15}.6\)                                  \(x=\frac{1}{4}+\frac{1}{3}\)                  \(5y-1952=553\)                                         

\(y=804\)                                           \(x=\frac{7}{12}\)                             \(5y=553+1952\)

                                                                                                                      \(5y=2505\)

                                                                                                                         \(y=2505:5=501\)

b) \(x+\frac{1}{2}=\frac{3}{4}\)                                      c)   \(3x+\frac{3}{8}=\frac{1}{2}\)

\(x=\frac{3}{4}-\frac{1}{2}\)                                                \(3x=\frac{1}{2}-\frac{3}{8}\)

\(x=\frac{1}{4}\)                                                              \(3x=\frac{1}{8}\)

                                                                                    \(x=\frac{1}{8}:3\)

                                                                                   \(x=\frac{1}{24}\)

           f)\(\left(8y-1942\right).1947=\left(240-194,2\right).19470\)

              \(\left(8y-1942\right).1947=45,8.19470\)

               \(\left(8y-1942\right)=45,8.19470:1947\)

                 \(8y-1942=45,8.10\)

                 \(8y-1942=458\)

                                      \(8y=458+1942\)

                                        \(8y=2400\)

                                              \(y=2400:8\)

                   \(y=300\)

=a, \(\dfrac{x}{15}\) = \(\dfrac{2}{5}\)

= \(x.5=15.2\)

=> \(x=\dfrac{15.2}{5}\)\(=\dfrac{30}{5}\) \(=6\)

Vậy \(x=6\)

b, \(\dfrac{3}{x-7}\) \(=\dfrac{27}{135}\)

= \(\dfrac{3}{x-7}\) \(=\dfrac{3}{15}\)

= \(x-7=15\)

\(x=15+7\)

\(x=22\)

vậy x = 22

c, \(320.x-10=5.48:24\)

= \(320x-10=240:24\)

= \(320x-10=10\)

= \(320x=10+10\)

\(320x=20\)

\(x=20:320\)

\(x=0,0625\)

d, \(5x-1952=\) \(2500-1947\)

\(5x-1952=553\)

\(5x=553+1952\)

\(5x=2505\)

\(x=2505:5\)

\(x=501\)

e, \(\left(x+1\right)+\left(x+2\right)+\left(x+3\right)+\left(x+4\right)\left(x+5\right)=45\)

= \(\left(x+x+x+x+x\right)\)+\(\left(1+2+3+4+5\right)\) \(=45\)

= \(5x+15=45\)

\(5x=45-15\)

\(5x=30\)

\(x=30:5\)

\(x=6\)

f, \(x-\dfrac{2}{3}-\dfrac{2}{15}-\dfrac{2}{35}-\dfrac{2}{63}=\dfrac{1}{9}\)

= \(x-\dfrac{2}{3}-\dfrac{2}{15}-\dfrac{2}{35}=\dfrac{1}{9}+\dfrac{2}{63}\)

= \(x-\dfrac{2}{3}-\dfrac{2}{15}-\dfrac{2}{35}=\dfrac{1}{7}\)

= \(x-\dfrac{2}{3}-\dfrac{2}{15}=\dfrac{1}{7}+\dfrac{2}{35}\)

= \(x-\dfrac{2}{3}-\dfrac{2}{15}=\dfrac{1}{5}\)

= \(x-\dfrac{2}{3}=\dfrac{1}{5}+\dfrac{2}{15}\)

= \(x-\dfrac{2}{3}=\dfrac{1}{3}\)

\(x=\) \(\dfrac{1}{3}+\dfrac{2}{3}\)

\(x=1\)

k, \(\dfrac{3+5+7+...+2015}{2+4+6+...+2014+x}=1\)

ta thấy phần tử là tập hợp các số lẻ ; phần mẫu là tập hợp các số chẵn

mà số chẵn hơn số lẻ 1 đơn vị

nên x thuộc tổng các số phần tử hơn mẫu là 1 đơn vị

=> từ \(2+4+6+...+2014\)có số số hạng là :

( 2014 - 2 ) : 2 + 1 = 1007

vậy x sẽ bằng :

( 1 + 1 ) . 1007 : 2 = 1007

vập số cần tìm là : 1007