Q.

If the range of the function f(x)=5xx23x+2, x1,2, is (,α][β,), then α2+β2 is equal to :          [2025]

1 190  
2 194  
3 188  
4 192  

Ans.

(2)

y=5xx23x+2, x1,2

 yx23xy+2y+x5=0

 yx2+(3y+1)x+(2y5)=0

Case I : If y = 0

 x = 5

Case II : if y 0

For real solutions, D0

 (3y+1)24(y)(2y5)0

 9y2+16y8y2+20y0

 y2+14y+10

 (y+7)2480

 |y+7|43  y+743 or y+743

 y437 or y437

From Case I and Case II, we have

    y(,437][437,)

  α=437 and β=437

 α2+β2=(437)2+(437)2=2(48+49)=194.