(b) $\int_{1}^{2}{f^{'}(x)}dx = \left\lbrack f(x) \right\rbrack_{1}^{2} = f(2) - f(1) = 0$ [$\because f(x)$ satisfies the condition of Rolle’s theorem ] $\therefore\ \ f(2) = f(1)$
Physics Educator & NEET/JEE Specialist
Ph.D. in Physics with 19+ years of teaching experience.