A(x):=(1-x)/4*(1+4*x^2);

diff(A(x),x,1);

ratsimp(%);

solve(%);

A(1/6);

fpprec : 4;

bfloat(A(1/6));

plot2d([A(x)], [x,0,0.5],[gnuplot_preamble, "set grid;"],
 [plot_format, gnuplot])$