求函数y=sin2x的二阶导数y''
A: y''=-4sin2x
B: y''=4sin2x
C: y''=-2sin2x
D: y''=-4cos2x
A: y''=-4sin2x
B: y''=4sin2x
C: y''=-2sin2x
D: y''=-4cos2x
举一反三
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