45 lines
1.1 KiB
Markdown
45 lines
1.1 KiB
Markdown
# 一、单选题：本题共8小题，每小题5分，共40分，每小题只有一个选项符合要求 1.样本数据2.8,14,16.20的平均数为
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A.8B.9C.12D.18
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2已知$z=1+i$ ，则$\frac{1}{z-1}=$
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A.-i B.i C.-1D.1
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3.已知集合$A=\{-4,0,1,2,8\}$ 上,$B=\left\{x\mid x^{3}=x\right\}$ ,则$A\cap B=$
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A.{0.1.2}B.{1,2.8}C.{2.8}D.{0.1}
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4.不等式$\frac{x-4}{x-1}\geq2$ 的解集是
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A.$\left\{x\mid-2\leqslant x\leqslant1\right\}$ B.$\{x|x\leqslant-2\}$ C.$\left\{x\mid-2\leqslant x<1\right\}$ D.$\{x\mid x>1\}$
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5.在△ABC中，$BC=2,AC=1+\sqrt{3},AB=\sqrt{6}$ ，则$A=$
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A.$45^{\circ}$ B.$60^{\circ}$ C.$120^{\circ}$ D.$135^{\circ}$
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6.设抛物线$C:y^{2}=2px(P>0)$ 的焦点为F，点A在C上，过A作C准线的垂线，垂足为B.若直线BF的方程为$y=-2x+2$ ，则$|AF|=$ ( )
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A.3B.4C.5D. 6
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7记$S_{n}$ 为等差数列$\{a_{n}\}$ 的前n项和，若$S_{3}=6.S_{5}=-5$ ,则$S_{6}=$
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A.$-20$ B.-15C.-10D.-5
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8.已知$0<\alpha<\pi,\cos\frac{\alpha}{2}=\frac{\sqrt{5}}{5}$ ，则$\sin(a-\frac{\pi}{4})=$
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A.$\frac{\sqrt{2}}{10}$ B.$\frac{\sqrt{2}}{5}$ C.$\frac{3\sqrt{2}}{10}$ D.$\frac{7\sqrt{2}}{10}$ |