MATLAB: Simple question about functions

MATLABmatlab function

function nFib = fib(n)
a = (1 + sqrt(sym(5)))/2;
nFib = (a^n)-((-a)^(-n)) / sqrt(sym(5)) ;
end
*The output for this function when n=3 is
fib(3)
ans =
5^(1/2)/(5*(5^(1/2)/2 + 1/2)^3) + (5^(1/2)/2 + 1/2)^3
Why isn't the answer showing the number but just the entire function itself? And how can I solve this problem to show the actual answer(in number)? Thank you!

Best Answer

function nFib = fib(n)
      a = (1 + sqrt(5))/2;
      nFib = a^n-(-a)^(-n) / sqrt(5) ;
end
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