Moment of inertia of a disc of mass M and radius ' R ' about any of...

Given here,

Moment of inertia of a disc of mass $M$ and radius '$R$' about any of its diameter is $\dfrac{M{R}^{2}}{4}$.

Moment of inertia of disc about centre is ${I}_{cm} = \dfrac{M{R}^{2}}{4} + \dfrac{M{R}^{2}}{4} = \dfrac{M{R}^{2}}{2}$

Using parallel axis theorem, we can write

$I = {I}_{cm} + M{d}^{2}$

$= \dfrac{M{R}^{2}}{2} + M{R}^{2}$

$= \dfrac{3}{2}M{R}^{2}$

Hence, the value of $x = 3$.