JEE Main20208 Jan 2020Evening ShiftMathematicsQuadratic EquationActual
Let S , be the set of all real roots of the equation, 3 x 3 x - 1 + 2 = 3 x - 1 + 3 x - 2 , then
Options
- Acontains exactly two elements.
- Bis a singleton.
- Cis an empty set.
- Dcontains at least four elements.
Correct answer
B. is a singleton.
Step-by-step solution
Let 3 x = t t t - 1 + 2 = t - 1 + t - 2 t 2 - t + 2 = t - 1 + t - 2 Let, f t = t 2 - t + 2   &   g t = t - 1 + t - 2 f t   &   g t has a solution at t = a . 3 x = a   ⇒ x = log 3 ⁡ a . So, it is a singleton set.