求值域(1)y=cos²x-4sinx+1 (2)y=sinxcosx+sinx+cosx
问题描述:
求值域(1)y=cos²x-4sinx+1 (2)y=sinxcosx+sinx+cosx
答
(1)y=-(sinx+2)²+6
故:值域为(-3,5)
(2)y=1-0.5(sinxcosx-1)²
sinxcosx∈(-√2,√2)
故:值域为(-2-2√2,2√2-2)