欧美日韩黄网欧美日韩日B片|二区无码视频网站|欧美AAAA小视频|久久99爱视频播放|日本久久成人免费视频|性交黄色毛片特黄色性交毛片|91久久伊人日韩插穴|国产三级A片电影网站|亚州无码成人激情视频|国产又黄又粗又猛又爽的

已知三角形的三邊按從小到大順序成等比數(shù)列,則公比q的范圍是(　　)

A.＜q＜1

B.1＜q＜

C. ＜q＜

D.0＜q＜

若f(x)=2x+3,則f(x+2)的表達式為…(　　)

A.2x+1　　　　　　

B.2x-1

C.2x-3

D.2x+7

試證:對于任意給定的向量a、b都有||a|-|b||≤|a+b|≤|a|+|b|.

已知△ABC中,AB=c,BC=a,AC=b,AB上的中線CD=m,求證:a²+b²=c²+2m².??

已知cos(θ-α)=a,sin(θ-β)=b.?

求證:cos²(α-β)=a²+b²-2absin(α-β).?

已知a、b∈R⁺,求證:≥.?

若a、b、c∈R⁺,求證:≥abc.?

已知a、b、c∈R⁺,求證:(ab+a+b+1)·(ab+ac+bc+c²)≥16abc.?

設(shè)f(x)=lg,其中a∈R.                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                        

如果0＜a≤1,求證:當(dāng)x≠0時,有2f(x)＜f(2x).

已知橢圓=1(a＞b＞0),A、B是橢圓上的兩點,線段AB的垂直平分線與x軸交于點P(x₀,0),求證:-.