16.

\(\lim\dfrac{u_n}{v_n}=+\infty\)

17.

\(SA\perp\left(ABC\right)\Rightarrow SA\perp AB\Rightarrow\Delta SAB\) vuông tại A (B đúng)

\(SA\perp\left(ABC\right)\Rightarrow SA\perp BC\) (C đúng)

\(\left\{{}\begin{matrix}SA\perp\left(ABC\right)\Rightarrow SA\perp BC\\AB\perp BC\left(gt\right)\end{matrix}\right.\) \(\Rightarrow BC\perp\left(SAB\right)\) (D đúng)

18.

Tập hợp điểm cách đều 2 điểm AB cho trước là mặt phẳng trung trực của AB

19.

\(\lim\limits_{x\rightarrow1}\dfrac{x-1}{2x-2}=\lim\limits_{x\rightarrow1}\dfrac{x-1}{2\left(x-1\right)}=\dfrac{1}{2}\)

D. Bị lệch về phía đáy

\(a,CH_2=CH-CH_3+H_2\rightarrow\left(Ni,t^o\right)CH_3-CH_2-CH_3\\ CH\equiv C-CH_3+2H_2\rightarrow\left(Ni,t^o\right)CH_3-CH_2=CH_3\\ b,CH\equiv C-CH_3+H_2\rightarrow\left(\dfrac{Pd}{PbCO_3}\right)CH_2=CH-CH_3\\ c,CH_2=CH-CH_3+Br_2\rightarrow\left(CCl_4\right)CH_2Br-BrCH-CH_3\\ CH\equiv C-CH_3+Br_2\rightarrow\left(CCl_4\right)CH_2Br=BrC-CH_3\)

\(d,CH\equiv C-CH_3+AgNO_3+NH_3\rightarrow AgC\equiv C-CH_3+NH_4NO_3\\ e,CH_2=CH-CH_3+H_2O\rightarrow\left(H^+\right)CH_3-CH_2-CH_2-OH\\ CH\equiv C-CH_3+H_2O\rightarrow\left(H^+\right)CH_2=CH-CH_2-OH\\ f,CH_2=CH-CH_3+HCl_{dư}\rightarrow CH_3-CHCl-CH_3\\ CH\equiv C-CH_3+HCl_{dư}\rightarrow CH_2=CCl-CH_3\)

A

It was said that many people were homeless after the flood.

Many people were said to be homeless after the flood.

It was thought that the company was badly damaged by the fire.

The company was thought to have been badly damaged by the fire.

Ta có : \(f\left(2\right)=2a+b-6\)

\(\lim\limits_{x\rightarrow2^+}\dfrac{x-\sqrt{x+2}}{x^2-4}=\lim\limits_{x\rightarrow2^+}\dfrac{x^2-x-2}{\left(x-2\right)\left(x+2\right)\left(x+\sqrt{x+2}\right)}\)  

\(=\lim\limits_{x\rightarrow2^+}\dfrac{x+1}{\left(x+2\right)\left(x+\sqrt{x+2}\right)}=\dfrac{3}{16}\)

\(\lim\limits_{x\rightarrow2^-}x^2+ax+3b=4+2a+3b\) 

H/s liên tục tại điểm x = 2 \(\Leftrightarrow\dfrac{3}{16}=2a+3b+4=2a+b-6\)

Suy ra : \(a=\dfrac{179}{32};b=-5\) => t = a + b = 19/32 . Chọn C 

Câu 33:

Chọn mp(SBD) có chứa DM

O∈BD⊂(SBD)

O∈AC⊂(SAC)

Do đó: O∈(SBD) giao (SAC)(1)

S∈(SBD)

S∈(SAC)

Do đó: S∈(SBD) giao (SAC)(2)

Từ (1),(2) suy ra (SBD) giao (SAC)=SO

Gọi I là giao điểm của DM và SO

=>I là giao điểm của DM và mp(SAC)

=>Chọn C