If y = a {x + √x² + 1}ⁿ + b{x – √x² + 1} ^{– n}, prove that (x² – 1) .

If y = A e ^{– kt} cos (pt + c), prove that , where n² = p² + k².

If , prove that

Find the second order derivatives of each of the following functions:

x³ + tan x

Find the second order derivatives of each of the following functions:

sin (log x)