For this form of equation, you can use contour function, or symbolic function ezplot, for the first solution you need to use meshgrid function and contour a solution at constant d ,as the following :
[x,y]=meshgrid(0:0.1:10);
a=4;b=1;c=2;
d=6;
f=a*y.^3+b*y-c*x-d;
contour(x,y,f,[d d],'k')
xlabel('x');
ylabel('y');
title(' f(x,y)=ay^3+by-cx-d')
