Question: Plot a function whose variable is in a function

I have the following two equations:

u=1-(8*(10.3968*t^2-5.8368*t*f-.229376*f^2-5.1984))/(4.56*t^2-2.56*t*f+.8192*f^2+2.28)^2;

x = f+t-(8*(-2.28*t+.64*f))/(2.28+2*(-t+.64*f)^2+2.56*t^2);

 

How can I plot

(i) a 2-dimensional graph that u versus x at t=0?

(ii) a 3-dimensional graph that u versus x and t ?

 

Thank you a lot for your help!

 

Please Wait...