99 Percentile Qs Bank for JEE MainMathematicsQuadratic Equation
If a + b + c > 9 c 4 and the equation a x 2 + 2 b x - 5 c = 0 has non-real complex roots, then
Options
- Aa > 0 , c > 0
- Ba > 0 , c < 0
- Ca < 0 , c < 0
- Da < 0 , c > 0
Correct answer
B. a > 0 , c < 0
Step-by-step solution
4 a + 4 b + 4 c - 9 c > 0 4 a + 4 b - 5 c > 0 f x = a x 2 + 2 b x - 5 c , D < 0 f 2 = 4 a + 4 b - 5 c > 0 a > 0 and - 5 c > 0 ⇒ c < 0 ⇒ a > 0 c < 0