4tg60°-sin60° = 4√3 - √3/2 = (8√3-√3) / 2 = 3.5√3
по дискриминанту
f'(x)=(6x-x^3)'=-3x^2+6
-3x^2+6=0
3x^2=6
x^2=2
x1=sqrt2
x2=-sqrt2
x є (-оо; -sqrt2] U [sqrt2; +oo)