If the roots of the equation be imaginary, then for all real values of , the expression is
- (A)greater than 4ab
- (B)less than 4ab
- (C)greater than - 4ab✓ Correct
- (D)less than - 4ab
Answer: (C)
Solution
Imaginary roots of mean its discriminant is negative, , so and hence . The expression opens upward because , so it has a least value . Since , the expression stays greater than for every real .
JEE Main · 2009 · 12 Apr 2009 · Offline · Single correct option