函数y=-x3+3x2+3的单调增区间是 .
考点分析:
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设f(x)=3ax
2+2bx+c,且a+b+c=0,,求证:
(1)若f(0)•f(1)>0,求证:-2<
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<-1;
(2)在(1)的条件下,证明函数f(x)的图象与x轴总有两个不同的公共点A,B,并求|AB|的取值范围.
(3)若a>b>c,g(x)=2ax
2+(a+b)x+b,求证:
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时,恒有f(x)>g(x).
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某人在一山坡P处观看对面山顶上的一座铁塔,如图所示,塔高BC=40(米),塔所在的山高OB=290(米),OA=210(米),图中所示的山坡可视为直线l且点P在直线l上,l与水平地面的夹角为α,
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.试问此人距水平地面多高时,观看塔的视角∠BPC最大(不计此人的身高).
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已知函数f(x)=
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sinωx•cosωx-cos
2ωx+
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(ω∈R,x∈R)的最小正周期为π,且图象关于直线x=
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对称.
(1)求f(x)的解析式;
(2)若函数y=1-f(x)的图象与直线y=a在[0,
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]上只有一个交点,求实数a的取值范围.
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已知△ABC的顶点A为(0,5),AB边上的中线所在直线方程为4x+11y-27=0,∠B的平分线所在直线方程为x-2y+5=0,求BC边所在直线的方程.
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已知向量
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=a=
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,
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=b=(2cosβ,2sinβ),其中O为坐标原点,且
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.
(1)若
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⊥(
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-
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),求β-α的值;
(2)当
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•(
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)取最小值时,求△OAB的面积S.
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