Try this:
x = linspace(-5, 5);
y = x.^2 .* exp(-(x.^2));
figure(1)
plot(x, y)
grid
Experiment to get the result you want. See the documentation on the various functions for details on what they can do and how to use them.
Also, you must use element-wise operations here. See the documentation on Array vs. Matrix Operations (link) for details.
