Question

Partea intreaga din 3x+1 este -4

[3x+1]=-4
cum se rezolva? am nevoie urgent!!

Answer 1

[3x+1]=-4

Stim ca: a-1<[a]≤a

=> 3x+1-1<-4≤3x+1

3x<-4≤3x+1

3x<-4 =>  x<-4/3; x∈(-∞; -4/3)

-4≤3x+1 => -5≤3x;   -5/3≤x; x∈[-5/3; +∞)

(-∞; -4/3)∩[-5/3; +∞) =[-5/3; -4/3]

x∈[-5/3; -4/3]