求函数的值域?
y=(cos3x-cosx)/cosx的值域?
y=(cos3x-cosx)/cosx =-2sin2xsinx/cosx =-4(sinx)^2*cosx/cosx =-4(sinx)^2 |sinx|=0=-4=-4=
y=(cos3x-cosx)/cosx =-2sin2xsinx/cosx =-4sinxcosxsinx/cosx =-4sin^x =2-4sin^x-2 =2cos2x-2 ∵cos2x∈[-1,1] ∴2cos2x-2∈[-4,0] 即:函数y=(cos3x-cosx)/cosx的值域为[-4,0]
试着用和差化积公式将分子化简,再做!!!!
答:1.f(x)=cos(x-π/3)-sin(π/2-x) =(1/2)cosx+(√3/2)sinx-cosx =(√3/2)sinx-(1/2)cosx =s...详情>>
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