Question

tìm x 

123 - 5 x ( x + 4 ) = 38

Answer 1

123 - 5 x ( x - 4 ) = 38 

        5 x ( x - 4 ) =123 - 38 

        5 x ( x - 4 ) = 85

              ( x - 4 ) = 85 : 5 

              ( x - 4 ) = 17 

                x        = 17 + 4

                x        = 21

vậy x = 21

Answer 2

123 - 5 x ( x + 4 ) = 38

5 x ( x + 4 ) = 123 - 38

5 x ( x + 4 ) = 85

( x + 4 ) = 85 : 5

x + 4 = 17

x = 17 - 4

x = 13

 Vậy x = 13

Answer 3

123 - 5 x ( x + 4 ) = 38

5 x ( x + 4 ) = 123 - 38

5 x ( x + 4 ) = 85

( x + 4 ) = 85 : 5

x + 4 = 17

      x = 17 - 4

      x = 13

Answer 4

123 - 5 x ( x - 4 ) = 38

5 x ( x - 4 ) = 123 - 38

5 x ( x - 4 ) = 85 : 5 

      ( x - 4 ) = 85 : 5

      ( x - 4 ) = 17

      x = 17 + 4 

      x = 21

Answer 5

123 - 5 x ( x - 4 ) = 38

5 x ( x - 4 ) = 123 - 38

5 x ( x - 4 ) = 85 : 5 

      ( x - 4 ) = 85 : 5

      ( x - 4 ) = 17

      x = 17 + 4 

      x = 21