Question

find d^2y/dx^2 in this case

Answer 1

$y = {x}^{3} + \tan(x) \\ \frac{dy}{dx} = 3 {x}^{2} + { \sec(x) }^{2} \\ \frac{ {d}^{2} y}{d {x}^{2} } = 6x + 2 \sec(x) ( \sec(x) \tan(x) ) \\ \frac{ {d}^{2}y }{d {x}^{2} } = 6x + 2 { \sec(x) }^{2} tanx$
hope this will help you.