question_answer

If a and b can take value 1, 2, 5, 6, then the number of the equations of the form \[a{{x}^{2}}+bx+1=0\] having real roots is

A)  11                               

B)  9     

C)  15                               

D)  None of these

Correct Answer: B

Solution :

(b): This will happen when \[{{b}^{2}}-4a\ge 0\] For (a, b) we have pairs