I

1. A ronot is a speacial kind of machine.

2. No, it isn't

3. Worker Robots can help make cars, and explore volcanoes, ...

4. No, it wasn't

II

1. No, there aren't. There are 2 kinds of sports.

2. Team sports require 2 separate teams.

3. Because they want to get the best score.

4. Yes, they are.

31.has not had

32.is

33.sang

34.loves

35.swim

is

sang

loves

swim

Gọi D là giao điểm BM và CN.

Trên cạnh BC lấy điểm E sao cho \(BE=BN\)

Khi đó \(CE=BC-BE=BN+CM-BE=CM\)

Xét hai tam giác BDE và BDN có: 

\(\left\{{}\begin{matrix}BE=BN\\\widehat{DBE}=\widehat{DBN}\left(\text{BM là phân giác}\right)\\BD\text{ chung}\end{matrix}\right.\)  \(\Rightarrow\Delta BDE=\Delta BDN\left(c.g.c\right)\)

\(\Rightarrow\widehat{BDE}=\widehat{BDN}\)

Hoàn toàn tương tự, ta cũng có \(\Delta CDE=\Delta CDM\left(c.g.c\right)\Rightarrow\widehat{CDE}=\widehat{CDM}\)

Mà \(\widehat{BDN}=\widehat{CDM}\) (đối đỉnh) \(\Rightarrow\widehat{BDN}=\widehat{BDE}=\widehat{CDM}=\widehat{CDE}\)

Mà \(\widehat{BDE}+\widehat{CDE}+\widehat{CDM}=180^0\)

\(\Rightarrow3\widehat{BDE}=180^0\Rightarrow\widehat{BDE}=60^0\)

\(\Rightarrow\widehat{CDE}=60^0\)

\(\Rightarrow\widehat{BDC}=\widehat{BDE}+\widehat{CDE}=120^0\)

Theo tính chất tổng 3 góc tổng tam giác:

\(\widehat{BDC}+\widehat{DBC}+\widehat{DCB}=180^0\)

\(\Rightarrow120^0+\dfrac{1}{2}\widehat{B}+\dfrac{1}{2}\widehat{C}=180^0\)

\(\Rightarrow\widehat{B}+\widehat{C}=120^0\)

Do tổng 3 góc trong tam giác ABC bằng 180 độ

\(\Rightarrow\widehat{A}+\widehat{B}+\widehat{C}=180^0\)

\(\Rightarrow\widehat{A}+120^0=180^0\)

\(\Rightarrow A=60^0\)

Lúc đầu, người bán hàng có: \(50\div\dfrac{2}{5}+1=126\) (trái)

Đ/s:..

Đợi tí, em nhầm :v

Lúc đầu, người bán hàng có: \(\left(50+1\right)\div\left(1-\dfrac{2}{5}\right)=85\)

21+3x−2=48

=>3�−2=48−21=>3x−2=48−21

=>3�−2=27=33=>3x−2=27=33

$=>x-2=3$

$=>x=5$

\(21+3^{x-2}=48\\ \Rightarrow3^{x-2}=27\\ \Rightarrow3^{x-2}=3^3\\ \Rightarrow x-2=3\\ \Rightarrow x=5.\)

thank you các bẹn

101.(-162)+38(-101)+101

= 101.(-162)-38.101+101=101.(-162-38+1)=101.(-199)=-20099