MATLAB: Solve for exponent variable

Question

syms x y z a b c Q N P S
Q= x^a
S = solve(Q==(x^4),a)
S-4
% why the answer is not zero and how to make it?

Answer 1

You need to specify the assumption that .

syms x y z a b c Q N P S
assume(x, 'positive')
Q = x^a
S = simplify(solve(Q==(x^4),a))
S-4