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化简f(x)=sin(2x+6/π)-sin(2x-6/π)-cos2x+1
函数f(x)=sin(2x+π/6)+sin(2x-π/6)-cos2x+1,求f(x)的最小正周期、对称轴、对称中心、单调增区间。
人气:251 ℃ 时间:2020-05-12 13:32:49
解答
6/π?通常是π/6啊,下面我当π/6来解吧:
f(x)=sin(2x+π/6)-sin(2x-π/6)-cos2x+1
=(sin2xcosπ/6+cos2xsinπ/6)-(sin2xcosπ/6-cos2xsinπ/6)-cos2x+1
=2cos2xsinπ/6-cos2x+1
=cos2x-cos2x+1
=1抱歉,一激动就把题目打得穿越了。补充了新的题目,不嫌弃的请重新回答一下,有理必采纳。对任意x∈R,恒有f(x)=1,是常数函数没有最小正周期【任何正实数都是它的正周期】对任意a∈R,x=a都是它的对称轴对任意a∈R,点P(a,0)都是它的对称中心没有严格单调递增区间。抱歉题目还是打错了,应该是:函数f(x)=sin(2x+π/6)+sin(2x-π/6)-cos2x+1,求f(x)的最小正周期、对称轴、对称中心、单调增区间。(x)=sin(2x+π/6)+sin(2x-π/6)-cos2x+1=(sin2xcosπ/6+cos2xsinπ/6)+(sin2xcosπ/6-cos2xsinπ/6)-cos2x+1=2(sin2x)cosπ/6-2cos2xsinπ/6+1=2sin(2x-π/6)+1最小正周期T=2π/2=πsin(2x-π/6)=1或-1,即2x-π/6=kπ+π/2,即x=kπ/2+π/3是对称轴,【k是整数,下同】sin(2x-π/6)=0,即2x-π/6=kπ,即x=kπ/2+π/12,点P(kπ/2+π/12,1)是对称中心sin(2x-π/6)=1,即2x-π/6=2kπ+π/2,x=kπ+π/3,T=π,单调递增区间为[kπ-2π/3,kπ+π/3]函数的最大值3,最小值-1,即值域[-1,3]
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