find the minimum value of y for positive vales of x

i have xmin=min(y(x>0)); where x=[-100:100] & y =x^3+60x^2-50 it gives me -50 which is wrong

aloso i have xmin=min(y(0:x(end))); where x=[-100:100] & y =x^3+60x^2-50 it gives me -50 which is wrong answer

any ideas? is my expression wrong ?

[per isakson]

I fail to run the code snippets of your question

Answer 1

[per isakson]

Try this

%%
x = (-100:100);
y = x.^3+60*(x.^2)-50;
%%
xmin = min(y(x>0))

which returns

xmin =
    11
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