高三数学题
已知函数f(x)=4sin2(π/4 +x)-2√3cos2x-1,且给定条件p:x<π/4或x>π/2,x∈R. ⑴在非p的条件下,求f(x)的最值; ⑵若条件q:-2<f(x)-m<2且非p是q的充分条件,求实数m的取值范围。
f(x)=4sin²(π/4 +x)-2√3cos2x-1 =-2[1-2sin²(π/4 +x)]-2√3cos2x+1 = -2cos(π/2 +2x)-2√3cos2x+1 =2sin2x-2√3cos2x+1 =4sin(2x -π/3)+1 1)非p的条件下 ,x∈[π/4 ,π/2] 则2x∈[π/2 ,π] 2x-π/3∈[π/6 ,2π/3] f(x)最小值=3 f(x)最大值=5 2)条件q f(x)-m =4sin(2x -π/3)+1-m∈(-2,2) 则,4sin(2x -π/3)+1∈(m-2,m+2) 非p的条件下2x-π/3∈[π/6 ,2π/3] 4sin(2x -π/3)+1∈[3,5] 非p是q的充分条件 ==>m>5或m5 ==〉m∈(5,7] mm∈[-3,3) ===>实数m的取值范围m∈[-3,3)∪(5,7] 。
答:应该是x∈R+吧。。。 f(x)=(x^2+ax+11)/(x+1)≥3对x∈R+恒成立 ===> x^2+ax+11≥3(x+1)=3x+3 ===> x^2...详情>>
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