JEE Main2013MathematicsQuadratic EquationActual
The real number k for which the equation, 2 x 3 + 3 x + k = 0 has two distinct real roots in [ 0 , 1 ] belongs to
Options
- Alies between - 1 and 0 .
- Bdoes not exist.
- Clies between 1 and 2 .
- Dlies between 2 and 3 .
Correct answer
B. does not exist.
Step-by-step solution
Given f x = 2 x 3 + 3 x + x ⇒ f ' x = 6 x 2 + 3 As f ' x > 0 for all x . ⇒ f x is a strictly increasing function for all x . Hence f x = 0 cannot have more than one root.