I am a new Mathimatica user and I need some help creating a script for fomula (3) as in the attached image. It is a modified Rayleigh method which calculated the natural frequency of a tapered offshore wind tower. Source Paper

Some variables:

x = height = 102 m , Yx = static deflection = ?x^3 L^-3 , E = youngs modulus = 210,000 N/mm² , ? = amplitude of bending , I1, I2, I3 = moment of inertia for each cross section , A1,A2,A3 = area for each cross section , ? = density of material = mass/ volume , M = mass of the blades and nacelle = 4MN , Jnb = moment of inertia of M