函数y=cos2x cosπ/5-2sinx cosx sin6π/5的递增区间如题,求递增区间.除了中间一个减号,其余都是乘号 A[kπ+π/10,kπ+3π/5] B[kπ-3π/20,kπ+7π/20] C[2kπ+π/10,2kπ+3π/5] D[kπ-2π/5,kπ+π/10]
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![函数y=cos2x cosπ/5-2sinx cosx sin6π/5的递增区间如题,求递增区间.除了中间一个减号,其余都是乘号 A[kπ+π/10,kπ+3π/5] B[kπ-3π/20,kπ+7π/20] C[2kπ+π/10,2kπ+3π/5] D[kπ-2π/5,kπ+π/10]](/uploads/image/z/2765062-46-2.jpg?t=%E5%87%BD%E6%95%B0y%3Dcos2x+cos%CF%80%2F5-2sinx+cosx+sin6%CF%80%2F5%E7%9A%84%E9%80%92%E5%A2%9E%E5%8C%BA%E9%97%B4%E5%A6%82%E9%A2%98%2C%E6%B1%82%E9%80%92%E5%A2%9E%E5%8C%BA%E9%97%B4.%E9%99%A4%E4%BA%86%E4%B8%AD%E9%97%B4%E4%B8%80%E4%B8%AA%E5%87%8F%E5%8F%B7%EF%BC%8C%E5%85%B6%E4%BD%99%E9%83%BD%E6%98%AF%E4%B9%98%E5%8F%B7+A%5Bk%CF%80%2B%CF%80%2F10%2Ck%CF%80%2B3%CF%80%2F5%5D+B%5Bk%CF%80-3%CF%80%2F20%2Ck%CF%80%2B7%CF%80%2F20%5D+C%5B2k%CF%80%2B%CF%80%2F10%2C2k%CF%80%2B3%CF%80%2F5%5D+D%5Bk%CF%80-2%CF%80%2F5%2Ck%CF%80%2B%CF%80%2F10%5D)
函数y=cos2x cosπ/5-2sinx cosx sin6π/5的递增区间如题,求递增区间.除了中间一个减号,其余都是乘号 A[kπ+π/10,kπ+3π/5] B[kπ-3π/20,kπ+7π/20] C[2kπ+π/10,2kπ+3π/5] D[kπ-2π/5,kπ+π/10]
函数y=cos2x cosπ/5-2sinx cosx sin6π/5的递增区间
如题,求递增区间.
除了中间一个减号,其余都是乘号
A[kπ+π/10,kπ+3π/5]
B[kπ-3π/20,kπ+7π/20]
C[2kπ+π/10,2kπ+3π/5]
D[kπ-2π/5,kπ+π/10]
函数y=cos2x cosπ/5-2sinx cosx sin6π/5的递增区间如题,求递增区间.除了中间一个减号,其余都是乘号 A[kπ+π/10,kπ+3π/5] B[kπ-3π/20,kπ+7π/20] C[2kπ+π/10,2kπ+3π/5] D[kπ-2π/5,kπ+π/10]
y=cos2x cosπ/5-2sinx cosx sin6π/5
=cos2x cosπ/5-sin2x sin6π/5…………【注意:sin6π/5=-sinπ/5 诱导公式】
=cos2x cosπ/5+sin2x sinπ/5
=cos(2x-π/5)
递增区间:2kπ+π
y=cos2xcosπ/5-2sinxcosxsin6π/5
y=cos2xcosπ/5-sin2xsin6π/5
y=cos2xcosπ/5+sin2xsinπ/5
y=cos(2x-π/5)
又因为余弦函数的递增区间是[π,2π],所以函数定义域就是
π<=2x-π/5<=2π
6π/5<=2x<=11π/5
6π/10<=x<...
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y=cos2xcosπ/5-2sinxcosxsin6π/5
y=cos2xcosπ/5-sin2xsin6π/5
y=cos2xcosπ/5+sin2xsinπ/5
y=cos(2x-π/5)
又因为余弦函数的递增区间是[π,2π],所以函数定义域就是
π<=2x-π/5<=2π
6π/5<=2x<=11π/5
6π/10<=x<=11π/10
若函数定义域是[0,2π]上就不用看后面的了
又因为这是一个周期函数,周期是π,
所以,函数的递增区间是[kπ+6π/10,kπ+11π/10] (k属于整数,)
楼上的不会做别说人家题错了
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