Q.

The sum of the squares of the roots of |x2|2+|x2|2=0 and the squares of the roots of x22|x3|5=0 is          [2025]

1 24  
2 36  
3 30  
4 26  

Ans.

(2)

We have, |x2|2+|x2|2=0

 |x2|2+2|x2||x2|2=0

 (|x2|+2)(|x2|1)=0

 |(x2)|=1          [  |x2|2]

 x=2±1  x=3,1

Sum of square of roots = 9 + 1 = 10

Now, we have x22|x3|5=0

Case I : When x – 3 > 0

 x22x+1=0  (x1)2=0  x=1

but x > 3  x1

Case II : When x – 3 < 0

 x2+2x11=0

Discriminant, D = 4 + 44 = 48 > 0

x = 2±482=2±432=1±23

SInce, x < 3, so both roots are valid.

Sum of squares of roots = (1+23)2+(123)2

     =1+1243+1+12+43=26

   Required sum = 10 + 26 = 36.