Sin(2arccos1/4)=2sin(arccos1/4)cos(arccos1/4)=2sqrt(1-1/16)*1/4=2sqrt(15)/16*1/4=sqrt(15)32
X^2 + 5x - 24 = 0
x1*x2 = p
x1 + x2 = -q
x1*x2 = -24
x1 + x2 = - 5
x1 = - 8
x2 = 3
Проверим:
x1*x2 = - 8*3 = 24
x1 + x2 = - (- 8 + 3) = 5
1)x=0 і x=1/3
2)x=0 і x=-7
3)x=0 і x=1/7
4)x=-3/2 і x=3/2
(3-5х)(1-2х+3х^2)=3-6х+9х^2-5х+10х^2-15х^3=3-11х+19х^2-15х^2
5 в квадрате = 25
вот так вроде