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下列求导正确的是( )
A.若\(y=\cos {\frac {1} {x}}\),则\({y}^{,}=-\frac {1} {{x}^{2}}\sin {\frac {1} {x}}\)
B.若\(y=\sin {{x}^{2}}\),则\({y}^{,}=2x\cos {{x}^{2}}\)
C.若\(y=\cos {5x}\),则\({y}^{,}=-5\sin {5x}\)
D.若\(y=\frac {1} {2}x\sin {2x}\),则\({y}^{,}=x\sin {2x}\)
参考答案:BC