Why symbolic variable usage takes time in matlab? How to remove it? -

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i have following code. 

syms x y; % line 1  %solve them parabola equation   = [ x^2 x y 1 ;x0^2 x0 y0 1; x1^2 x1 y1 1; x2^2 x2 y2 1];  %line 2  s = solve(det(a),y); %line 3

(x1,y1), (x2,y2), (x3,y3) integer coordinates.

the line 2 takes 0.48 seconds 73 calls , line 3 takes 1.5 seconds 73 calls.

in line 2 defining matrix. why time in line 1?

also suggestions on decreasing time?

thanks


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