using Plots
x = collect(1:7)
y(x) = 2 - 2x + x^(2/4)
plot(1,2)
LoadError: LoadError: UndefVarError: _gr_seriestype not defined line 4
I can’t reproduce this error, can you post the output of versioninfo() and your version of Plots.jl and GR.jl?
More generally, I’m not sure what you’re trying to achieve but if you’re trying to plot the function y(x) over the interval 1 to 7, you should do:
plot(x, [y(a) for a in x])
in your last line