Ta có:

^A-^B=18°

^B-^C=18°

=>^A-^B+^B-^C=18°+18°

=>^A-^C=36°

=>^C=^A-36°

Vì ^A-^B=18°

=>^B=^A-18°

Xét ΔABC có: ^A+^B^C=180°(đl tổng ba góc tam giác) 

=>^A+^A-18°+^A-36°=180°

=>3^A=234°

=>^A=78°

=>^B=78°-18°=60°

=>^C=78°-36°=42°

Từ  \(\frac{a+b-c}{c}=\frac{a-b+c}{b}=\frac{-a+b+c}{a}\)

\(\Rightarrow\frac{a+b-c}{c}+2=\frac{a-b+c}{b}+2=\frac{-a+b+c}{a}+2\)

\(\Rightarrow\frac{a+b+c}{c}=\frac{a+b+c}{b}=\frac{a+b+c}{a}\)

Nếu a + b + c = 0

=> a + b = - c

=> b + c = - a

=> c + a = - b

Khi đó \(\frac{\left(a+b\right).\left(b+c\right).\left(c+a\right)}{abc}=\frac{-a.\left(-b\right).\left(-c\right)}{abc}=-\frac{abc}{abc}=-1\)

Nếu \(a+b+c\ne0\)

\(\Rightarrow\frac{1}{c}=\frac{1}{b}=\frac{1}{a}\)

\(\Rightarrow a=b=c\)

Khi đó \(\frac{\left(a+b\right).\left(b+c\right).\left(c+a\right)}{abc}=\frac{2a.2b.2c}{abc}=\frac{8.abc}{abc}=8\)

Vậy nếu a + b + c = 0 thì \(\frac{\left(a+b\right).\left(b+c\right).\left(c+a\right)}{abc}=-1\) 

nếu a + b + c \(\ne\)0 thì  \(\frac{\left(a+b\right).\left(b+c\right).\left(c+a\right)}{abc}=8\) 

1. The hotel in New York was better than the hotel in California.

\(\rightarrow\)The hotel in the California wasn't as good as the hotel in New Year.

2. French is easier than German.

\(\rightarrow\)German isn't as easy as French

3. Rick is frienlier than Glenn.

\(\rightarrow\)Glenn isn't as friendly as Rick

4. Indonesia is hotter than VietNam.

\(\rightarrow\)Viet Nam isn't as hot as Indonesia

5. Football is more exciting than voleyball.

\(\rightarrow\)Volleyball isn't as exciting as football.

              ~ Hk tốt ~

\(3\cdot\left(5x+\frac{2}{3}\right)^2=\frac{4}{3}\)

\(\left(5x+\frac{2}{3}\right)^2=\frac{4}{3}:3\)

\(\left(5x+\frac{2}{3}\right)^2=\frac{4}{3}\cdot\frac{1}{3}\)

\(\left(5x+\frac{2}{3}\right)=\frac{4}{9}\)

\(\rightarrow\left(5x+\frac{2}{3}\right)^2=\left(\frac{2}{3}\right)^2\)

\(\rightarrow5x+\frac{2}{3}=\frac{2}{3}\)

\(5x=\frac{2}{3}-\frac{2}{3}\)

\(5x=0\rightarrow x=0\)

- Câu sai chính là câu: 

= AVEGAGE(12,13,14)

- AVERAGE là hàm tính trung bình cộng của một dãy các số

Còn câu 2 mk ko hiểu bạn định hỏi gì