1/9 x^2-x+2=0 (домножим обе части на 9)
x^2-9x+18=0
По Th Виетта:
x1=6
x2=3
-3x +1 +0,5 = 1.5x
-4.5x = -1,5
x = 1.5/4.5
x = 1/3
3x +0.4 = 0.4 - 1.6x
4.6x = 0
x=0
У'=5х^4+((х^5-1)-5х^5)/(х^5-1)^2=-(1+6х^5)/(х^5-1)^2
Вроде так
Решение
1 + cos(x + π/2) + cos(x - π/2) =
= 1 - sinx - sinx = 1 - 2sinx
при x = 5π/12
1 - 2sinx = 1 - 2sin(5π/12) = 1 - 2sin75° = 1 - 2 * 0,9659 = 1 - 1,9318 = - 0,9318