Eliminate the parameter t to find a Cartesian equation in the form x=f(y) for:
{x(t)=2t^2
y(t)=3+4t
y = 3+4t, so t = (y-3)/2
Now you have
x = 2t^2 = 2((y-3)/2)^2 = 1/2 (y-3)^2
{x(t)=2t^2
y(t)=3+4t
Now you have
x = 2t^2 = 2((y-3)/2)^2 = 1/2 (y-3)^2