函數(shù)f(x)=cos2x+2sinx的最小值和最大值分別為( ) A.-3,1 B.-2,2 C.-3,32 D.-2,32
函數(shù)f(x)=cos2x+2sinx的最小值和最大值分別為( ?。?br/>A. -3,1
B. -2,2
C. -3,
D. -2,
優(yōu)質(zhì)解答
∵
f(x)=1?2sin2x+2sinx=?2(sinx?)2+,
∴當(dāng)
sinx=時(shí),
fmax(x)=,
當(dāng)sinx=-1時(shí),f
min(x)=-3.
故選C.
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