If both a and b belongs to the set {1,2,3,4 }, then the number of equations of the form ax2 + bx + 1 = 0 having real roots is  Options:
A) 10 B) 7 C) 6 D) 12 E) 15
Explanation :   ax2 + bx + 1 = 0 .   For real roots   =&gt; b2 -4ac ≥ 0 .   i.e b2 - 4a(1) ≥ 0 .   i.e b2 ≥ 4a.   For a = 1, 4a = 4, ∴ b = 2, 3, 4   a = 2, 4a = 8, ∴ b = 3, 4   a = 3, 4a = 12, ∴ b = 4   a = 4, 4a = 16, ∴ b = 4   ∴ Number of equations possible = 7.   Harsh Mishra a year ago   0 upvotes   Answer : 7
<result>B</result>
If both a and b belongs to the set {1,2,3,4 }, then the number of equations of the form ax2 + bx + 1 = 0 having real roots is