Question

If p, q Ī {1, 2, 3, 4}, the number of equations of the form

px² + qx + 1 = 0 having real roots is–

• A. 15
• B. 9
• C. 7
• D. 8

Answer 1

Answer: (C)

7

Answer 2

For real roots D ³ 0 Ž q² – 4p ³ 0 Ž q² ³ 4p

If p = 1 Ž q = 2, 3, 4

p = 2 Ž q = 3, 4

p = 3 Ž q = 4

p = 4 Ž q = 4

Ž 7 equations