1.(-34;-14)
1. 2x-y=6 => 2x=6+y => y=3+0.5x
2. x-3y=8 => x-3(3+0.5x)=8 => x-9-1.5x=8 => -0.5x=17 => x=-34
3.y=3+0.5x =>y=3+0.5*(-34) => y=3-17 => y=-14
<span>(2х+1)(2х-1)^2 +(1-2х)^3 =
(2x+1)(4x^2 -2x +1) -8x^3 +12x^2 -6x +1 =
8x^3 -4x^2 -2x +1 </span>-8x^3 +12x^2 -6x +1 =
8x^2 -8x +2
Cos(5π/7) = -cos(2π/7)
- 8sin (π/7) * cos (π/7) * cos (2π/7) * cos (4π/7) = - sin (8π/7)
<span>- sin (8π/7) / 8sin (π/7) = 1/8</span>
2х^2+14х-30х+5х^2
7х^2-16х
х(7х-16) вот)