X^2+3x=0
X(X+3)=0
X=0 или X+3=0
X=-3
y=5
+3x-2
y'=10x+3
y'=0
10x+3=0
10x=-3
x=-0,3 - точка экстремума
A²(27-a³)=a²(3-a)(9+3a+a²)
Сos(a+b) = <span>сos a*cos b - sin a*sin b.</span><span>
Находим cos a = </span><span>√(1-(64 / 289)) = 15 / 17.
</span>sin b = √(1-(9/25)) = 4 / 5.
<span>cos(a+b) = (15 / 17)*(3 / 5) - (8 / 17)*(4 / 5) = (45-32) / 85 = 13 / 85</span>