Question

Tìm  x, biết rằng:

a)  5 8 x + 2 5 = 1 5

b)  5 7 : x + 11 7 = 18 7

c)  2 x 5 − 1 : − 5 = 1 7

Answer 1

a) 

5 8 x + 2 5 = 1 5 5 8 x             = 1 5 − 2 5 5 8 x            = − 1 5 x               = − 1 5 : 5 8 x                = − 1 5 . 8 5 x               = − 8 25

b)

5 7 : x + 11 7 = 18 7 5 7 : x            = 18 7 − 11 7 5 7 : x             = 1 x                 = 5 7 : 1 x                = 5 7

c)

2 x 5 − 1 : − 5 = 1 7 2 x 5 − 1         = 1 7 . − 5 2 x 5 − 1       = − 5 7 2 x 5              = − 5 7 + 1 2 x 5              = 2 5 x                 = 2 5 : 2 5 x                 = 1