Question

Tìm x:   (2.|x|-1).(7-3x)=0. ;  (x^2+1).(1/2-3x)<0. ;  (|x|+1).(15x-1)=0.     

Answer 1

( 2. l x l - 1) .(7 - 3x ) =0                                        ( x² + 1 ). ( 1/2 - 3x ) <0                                  ( l x l + 1 ) . ( 15x - 1 ) = 0

=> 2 . l x l - 1 = 0 hoặc 7 - 3x = 0                           => x²+1 hoặc 1/2 -3x < 0                              => l x l + 1 hoặc 15x - 1 =0

+  2 . l x l - 1 = 0 => 2 . l x l =1 => x = 1/2             + x² +1< 0 => x không tồn tại                       + l x l - 1 = 0 => l x l = 1 => thuộc 1 : -1

+ 7 - 3x = 0 => 3x = 7 => x = 7/3                           + 1/2 - 3x < 0 => 3x > 1/2 => x > 1                 + 15x - 1 = 0 => 15x =1 => x = 1/15