∈01时,ylogax递减∴只有D正确a∈01ylogax递减yxa过11点、递增、且是凸的所以,选D
8记maxxy
xxyyxy,mi
xy,设ab为平面向量,则(xxyyxy
)
Ami
ababmi
abBmi
ababmi
abCmi
ab
2
ab2a2b2ab2a2b2
Dmi
ab【答案】D【解析】
2
a±b2ab±2ab,∴不论ab正负零,ab2ab和ab2ab中总有一个≥ab即maxab2ab2≥ab其它都不对选D
2222
2
2
2
2
2
2
9已知甲盒中仅有1个球且为红球,乙盒中有m个红球和
个篮球m3
3,从乙盒中随机抽取ii12个球放入甲盒中(a)放入i个球后,甲盒中含有红球的个数记为
i
i12;
(b)放入i个球后,从甲盒中取1个球是红球的概率记为pii12
f则Ap1p2E1E2Cp1p2E1E2【答案】A【解析】Bp1p2E1E2Dp1p2E1E2
令m3
3131从乙中取1个后,甲中的红球可能是12,概率均为∴Eξ122从乙中取2个后,甲中的红球可能是321,概率qq373780592分别p3
11C326C3C318C3263621816p2p1∴Eξ22222C630C630C63030
∴Eξ2Eξ12从乙中取1个后,再从甲中取1个,是红球的概率p11113222461826120从乙中取2个后,再从甲中取1个,是红球的概率p23030330330∴p1p2选A
1isi
2x,aii01299,399
2210设函数f1xx,f2x2xxf3x
记Ikfka1fka0fka2fka1fka99fka98,k123则AI1I2I3【答案】【解析】BBI2I1I3CI1I3I2DI3I2I1
fai1ai
i1i12i1ai1ai9999999912i122f1ai1f1aiai1ai9999
I1f1a1f1a0f1a2f1a1f1a99f1a98
113298119999
22i12982i1)99999999I2f2a1f2a0f2a2f2a1f2a99f2a98f2ai1f2ai2ai1aiai1ai
22
222004998960298298491999999999999
1i1if3ai1f3aisi
2πsi
2π39999I3f3a1f3a0f3a2f3a1f3a99f3a9812574825r