x*(1/4)-4*(1/x)+2
производная равна (1/4)+4/(x^2)
<span>sinAsin(A+B) + cosAcos(A+B)=cos(A-A-B)=cos(-B)=cosB</span>
<span>cos(A+B) + cos(A-B)=cosAcosB - sinAsinB + cosAcosB + sinAsinB = 2cosAcosB </span>
3*SinxCosx - Sinx = 0
Sinx(6Cosx -1) = 0
Sinx = 0 6Cosx -1 = 0
x = πn , n ∈Z Cosx = 1/6
x = +-arcCos(1/6) + 2πk , k ∈Z