Question: Plotting with a constant

Hello, I have a problem with plotting graphs with a constant.. I have one system of equations and one another equation:

dx/dt=x(t)

dy/dt=ky(t)

and 

|y|=C|x|^k

I need to compare theit curves.

k and C are constants. I thought it is alright if I would remove constants, BUT there is one in the power, so I have no idea what to do.. 

I just tried to plot the system, but it doesn't work either:

> DE := [diff(x(t), t) = x(t)];
                    
> DF := [diff(y(t), t) = y(t)];
                     
> with(DEtools); DC := sin(x(t))/sin(t); dfieldplot({DE, DF}, {x(t), y(t)}, 
t = -10 .. 10, x = -10 .. 10, y = -10 .. 10, arrows = medium, title = 'Diff', color = DC);

Error, (in DEtools/dfieldplot) DEs must be a set of algebraic equations or procedures.