Question: SHM plotting

This is on Simple Harmonic Motion. I have
KE= 2*v(t)^2 ,
PE= 3*x(t)^2 + 4*x(t)^4.       and I also have given
diff(x(t),t) = v(t).

I needed help plotting it because I know that TE = PE + KE is a constant and I just want to plot it into a straight line. ( I have simplified the equations so don't worry about the equations being wrong).

 

Help Needed, really appreciated.

 

Thanks, 

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