<span>А) sin 80 cos 21 – cos 81 sin 21=sin(81-21)=sin60=V3/2</span>
С(-0,2)
в(-1,5)
D(0,6)
a(1,5)
Вот, надеюсь разберете)))))
(4x^3 + 7x^2 - x) * (-5)
-20x^3 - 35x^2 + 5x |:(-5x)
4x^2+7x-1
4x^2 + 7x - 1 = 0
D = 49 + 16 = 65
x1 = (-7 + корень(65)) / 8 = 0.132
x2 = -1.882