Show that an equation of the tangent to c at p is y 2x - 2

Question

The curve C has equation

y = arsinh (x³),                   x ≥ 0.

The point P on C has x-coordinate √2.

(a) Show that an equation of the tangent to C at P is

y = 2x - 2 √2 + In(3+ 2√2).

The tangent to C at the point Q is parallel to the tangent to Cat P.

(b) Find the x-coordinate of Q, giving your answer to 2 decimal places.