Question

tìm x,biết |2x - 5| = 13 - x

Answer 1

|2x - 5| = 13 - x

TH1 : 2x-5 = 13-x

=> 2x = 13 - x + 5

=> 2x = 13+5-x

=> 2x = 18 - x 

=> 18 = 2x + x 

=> 18=3x 

=> x = 6

TH2 : 2x - 5 = - (13-x)

=> 2x = -13 + x + 5

=> 2x = -13 + 5 + x

=> 2x - x = -8

=> x = -8 

Answer 2

Th1:

2x-5 = 13-x

2x = 18

x= 9

Th2:

-(2x -5) = 13-x

-2x +5 = 13-x

-x = 8

x= -8

Vậy x= 9 và x= -8