найти экстремум

cos(pi\3+a)cos a + sin(pi\3+a)sin a= 0,5

при каких а уравнение имеет решения 5cos3x + 12sin3x = a - 5

y=x*3+1/cosx найти производную

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четность/нечетность в)найти точки пересечения с осями координат г)найти экстремумы и интервалы монотонности д)найти точки перегиба и интервалы выпуклости и вогнутости е)найти пределы при х стремящемся к +-бесконечности ж)построить график функции

y=2x^3-3x^2