y = cos2x + sin²x - cosx
= cos²x - cosx
= (cosx - 1/2)² - 1/4
x = 2kπ + π ,max(y) = 2
x = 2kπ ± π/3 ,min(y) = -1/4
x∈[0,2π]
x ∈ {π} ,max(y) = 2
x ∈ {π/3 ,8π/3} ,min(y) = -1/4
已知函数y=cos2x+sin方x-cosx
y = cos2x + sin²x - cosx
= cos²x - cosx
= (cosx - 1/2)² - 1/4
x = 2kπ + π ,max(y) = 2
x = 2kπ ± π/3 ,min(y) = -1/4
x∈[0,2π]
x ∈ {π} ,max(y) = 2
x ∈ {π/3 ,8π/3} ,min(y) = -1/4