Q.

The set of all a for which the equation x|x-1|+|x+2|+a=0 has exactly one real root, is          [2023]

1 (-,)  
2 (-6,)  
3 (-,-3)  
4 (-6,-3)  

Ans.

(1)

Let f(x)=x|x-1|+|x+2|

Given, x|x-1|+|x+2|+a=0

 f(x)+a=0-a=f(x)

f(x)={-x2-2,-<x<-2 -x2+2x+2,-2x<1x2+2,1x<

All values are increasing.