(c) Given, $f(x) = be^{ax} + ae^{bx}$ $\Rightarrow \ \ \ f^{'}(x) = \ abe^{ax} + abe^{bx}\$ $\Rightarrow \ \ \ f^{''}(x) = a^{2}be^{ax} + ab^{2}e^{bx}$ $\Rightarrow \ \ \ {\ f}^{''}(0) = a^{2}b + ab^{2} = ab(a + b)$
Physics Educator & NEET/JEE Specialist
Ph.D. in Physics with 19+ years of teaching experience.