2х²-4ху²+3ху-6у³=2x(x-2y²)+3y(x-2y²)=(2x+3y)(x-2y²)
При <span>х=1/4,у=1/6
</span>(2*1/4+3*1/6)(1/4-2*(1/6)²)=(1/2+1/2)(1/4-2/36)=1*7/36=7/36
вроде так
<span> 1/sina-1 - 1/sina+1=(sina+1-sina+1)/(sina-1)(sina+1)=2/(sin</span>²a<span>-1)=-2/cos</span>²a
-tgx>√3
tgx<-√3
x⇒(-π/2+πn;-π/3+πn)
4х - 28 = 0
4х = 28 + 0
4х = 28
х = 28 : 4
х = 7
Удачи)