$\"\"$

The function is $\"\"$ .

Apply first derivative on each side.

$\"\"$

Apply formulas : $\"\"$ and $\"\"$ .

$\"\"$

Apply second derivative on each side.

$\"\"$

Apply third derivative each side.

$\"\"$

Apply fourth derivative each side.

$\"\"$

Substitute $\"\"$ in the above equation.

$\"\"$

Hence the function $\"\"$ is a solution of differential equation $\"\"$ .

$\"\"$

The function $\"\"$ is a solution of differential equation $\"\"$ .