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NT
1
Những câu hỏi liên quan
VH
2
LD
6 tháng 4 2023
\(x^2-2\left(m-2\right)x+m^2+2m-3=0\left(1\right)\)
Để phương trình có hai nghiệm phân biệt thì Δ' > 0
\(\Rightarrow\left(m-2\right)^2-m^2-2m+3>0\Leftrightarrow m^2-4m+4-m^2-2m+3>0\Leftrightarrow-6m+7>0\Leftrightarrow m< \dfrac{7}{6}\)\)
Theo viét : \(\(\left\{{}\begin{matrix}x_1+x_2=2\left(m-2\right)\\x_1x_2=m^2+2m-3\end{matrix}\right.\)\)
Lại có :\( \dfrac{1}{x_1}+\dfrac{1}{x_2}=\dfrac{x_1+x_2}{5}\)
\(\Leftrightarrow\dfrac{x_1+x_2}{x_1x_2}=\dfrac{x_1+x_2}{5}\)
\(\Rightarrow\left(x_1+x_2\right)\left(x_1x_2\right)=5\left(x_1+x_2\right)\)
\(\Leftrightarrow\left(2m-4\right)\left(m^2+2m-3\right)=5\left(2m-4\right)\)
\(\Leftrightarrow2m^3+4m^2-6m-4m^2-8m+12=10m-20\)
\(\Leftrightarrow2m^3-24m+32=0\) \(\Leftrightarrow\left[{}\begin{matrix}m=-4\left(n\right)\\m=2\left(l\right)\end{matrix}\right.\)
Vậy \(m=-4\) thì thỏa điều kiện
KC
0
DC
6
1N
4
17 tháng 12 2021
(55 – 737) – ( 463 – 45 + 38) =-682 - 456 = -1138
TN
1
NT
2
17 tháng 8 2016
So sánh nguyên nhân và kết quả:
1) When you read more books, you will get more knowledge
- The more books ........................
2) When I get older , I am happier
-The older..................................
3) If the weather is warmer , I feel better
-The warmer......................................
4) If the hotel is more expensive , it will server better
- The more..............................
5) When you use more electricty , you bill will be higher
-The more...............................
6) If we spend much time thinking , we won't have enough time to do
-The more time to...............................
7) As you are aged , you becomes weak and slow
-The older
8)When technology is morden , the world's environment becomes worse and worse
-The more.........................
SQ
1
NH
X. Em hãy sắp xếp những câu sau thành câu có nghĩa:
1.Linh's family doesn't have a TV because they like to talk all evening.
2.Would you like to have dinner at my house tonight?
3.We are going to see a detective movie with our parents this afternoon.
4.Thirty years ago in Vietnam, very few people had TV sets.
5.Why don't you like the programs for teenagers?
6.Young people like to hear the lastest pop music and see the shows of their favorite artists.
7.With satellite and cable TV, it's posible to choose from a wide variety of programs.
8.My brother prefers watching TV to reading books.
9.What kinds of TV program does the daughter like best?
10.There is a horror film showing at the local cinema next week.
Góc đố vui
GUESS THE SUBJECT:
1.painting/picture
2.telephone/phone
3.knife
4.wind
5.football/soccer
6.snow
7.tooth
8.library
9.dictionary
10.television