Harmonic Progression

Given a, b, c (taken in the order) are in arithmatic progression b, c, d (taken in this order) are in geometric progression and c, d, k (taken in this order) are in Harmonic progression. If a= 2 and k = 18 then possible values of 'c' can be

Let a,b be positive real numbers.If aA_(1),A_(2),b be are in arithmetic progression a,G_(1),G_(2),b are in geometric progression,and a,H_(1),H_(2),b are in harmonic progression,show that (G_(1)G_(2))/(H_(1)H_(2))=(A_(1)+A_(2))/(H_(1)+H_(2))

In the equation of a simple harmonic progressive wave of wavelength 'lamda' , the propagation constant is given by

The equation of a simple harmonic progressive wave along the negative direction of X-axis is

In a simple harmonic progressive wave, the maximum particle velocity is twice the wave velocity. If lamda is the wavelength, then its amplitude is given by

When a simple harmonic progressive wave is propogating the medium, all the particles of the medium vibrate with

The equation of a simple harmonic progressive wave along the positive direction of X axis is given by