r is a constant.

It's a group velocity curve, and i want to know how y(velocity) changes when x(frequency) varies in the real field only.

clear
clc
a1=7800;
b1=9.05*10^10;
c1=8.59*10^10;
Cl=sqrt((b1+2*c1)/a1);
Ct=sqrt(c1/a1);
r=Cl/Ct;
[x, y] =solve('((2*y*(y/r^2-x)^0.5*besselj(1,(y/r^2-x)^0.5)*besselj(1,(y-x)^0.5))-((y-2*x)^2*besselj(0,(y/r^2-x)^0.5)*besselj(1,(y-x)^0.5))-(4*x*(y/r^2-x)^0.5*(y-x)^0.5*besselj(1,(y/r^2-x)^0.5)*besselj(0,(y-x)^0.5)))=0','y');