2由ax1?2x1?a?0,得a?2x11,且?x1?1. x12?1e2x1x12?1122x1x12?12?21nx1?4(2?1nx1). M?22x1?x1?12x1?1x122设x1?t,
1t?11,令?t?1?(t)?4(?1nt),
e2t+1221?2(t?1)2??(t)?4(?)??0, 22(t+1)2tt(t?1)11上单调递减,从而,1)?(1)??(t)??(), e2e28所以,实数M的取值范围是(0,2).
e?1?(t)(在(高二数学Ⅱ(附加题)
21. 解(1)由题知MN???2 ?1??1 1??0 3??0 3?,所以?det(MN)???2 ?1??7 ?2??7 ?2???2l,
1 3?????????21? ??217?1根据逆矩阵公式,得(MN)???.
?1 0????3?(2)设由L上的任意一点P?(x?,y?)在T作用下得到L?上对应点p(x,y).
3x+y??x???2 ?1??x???x??2x??y??x,?7由?,即解得, ???????????2y?x?1 3??y??y??x?3y?y'?y'??7?因为2x??y??1?0,所以2?即5x?4y?7?0.
即直线L的方程为5x?4y?7?0.
3x?y2y?x??1?0, 77?x2?x?3cos?,?y2?1, 22.解(1)由?得C:3??y?sin?,由pcos?(???4)?22,得pcos??psin??4,即l:x?y?4?0.
x2?y2?1上任取一点P(3cos?,sin?)(0???2?), (2)在C:3则点P到直线l的距离为d?|3cos??sin??4|2|2sin(????3)?4|,0???2?,
2当sin(???3)??1,即??7?时,dmax?32. 623. 解(1)设事件A:“恰用完3次投篮机会”,则其对立事件A:“前两次投篮均不中”, 依题意, P(A)?1?P(A)?1?(1?p)?解得p?221, 253. 5(2)依题意, X的所有可能值为0,1,2,3, 且P(X?0)?(1?p)?24, 2524, 125P(X?1)?p(1?p)2?(1?p)p(1?p)?P(X?3)?p3?27, 12554. 125故P(X?2)?1?P(X?0)?P(X?1)?P(X?3)?X的概率分布列为:
数学期望E(X)?245427213. ?2??3??12512512512524.解(1)如图,以D为坐标原点,分别以直线DA,DC,DD1所在直线为x轴, y轴, z轴,建立空间直角坐标系D?xyz,
AE?(0,2,a), 易得A1B?(0,2,?3),设BE?a,则
因为A1B?AE,所以AB1?AE?(0,2,?3)? (0,2,a)?4?3a?0, 解得a?44,即AE?(0,2,), 33又D1B?(2,2,?3),AC?(?2,2,0),
所以D1B?AE?(2,2?3)? (0,2,)?0,所以D1B?AE, 且D1B?AC?(2,2,?3)?(?2,2,0)?0,所以D1B?AC, 又AE43AC?A,所以D1B?平面AEC.
43(2) AE?(0,2,),D1A?(2,0,?3),DC?(0,2,?3), 1设平面ACD1的一个法向量n?(x,y,z),
??D1A?n?0,?2x?3z?0,则?即?
2y?3z?0,??D1C?n?0,?令z?0,则x?y?3,即n?(3,3,2),
sin??|cos?AE,n?|?AE?n
|AE|?|n|?42?3=?22863=. 22422+()2?32+32+223
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