Q.

If α and β(α<β) are the roots of the equation x2+bx+c=0, where c<0<b, then                       [2000]

1 0<α<β  
2 α<0<β<|α|  
3 α<β<0  
4 α<0<|α|<β  

Ans.

(2)

Given : c<0<b and α+β=-b           ⋯(i)

αβ=c    ⋯(ii)

From (ii), c<0⇒αβ<0⇒Either α is negative or β is negative and second quantity is positive.

From (i), b>0⇒-b<0⇒α+β<0

⇒the sum is negative

⇒(Modulus of negative quantity)>(Modulus of positive quantity)

But given α<β. Therefore, it is clear that α is negative and β is positive

and modulus of α is greater than modulus of β

⇒α<0<β<|α|