<span>cos(π/5)*cos(2π/5)</span><span><span>=<span><span>sin(π/5)*cos(π/5)*cos(2π/5)/</span><span>sin(π/5)</span></span></span><span>=<span><span>sin(2π/5)*cos(2π/5)/</span><span>2sin(π/5)</span></span></span><span>=<span><span>sin(4π/5)/</span><span>4sin(π/5)</span></span></span><span>=<span>1/4</span></span></span>
Решение во вложениях)))))))))))
F(x)=3x²-2x³+6
f `(x)=(3x²-2x³+6)`=3*2x-2*3x²=6x-6x²=6x(1-x)
f `(x)=0 при 6x(1-x)=0
x=0 1-x=0
x=1
- + -
___________0____________1______________
↓ min ↑ max ↓
x(min)=0 и x(max)=1 - это точки экстремума
f(x) - монотонно убывает на х∈(-∞;0)U(1;+∞)
f(x) - монотонно возрастает на x∈(0;1)