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h) Ta có: \(\left\{{}\begin{matrix}\left|x-7\right|=\left|7-x\right|\ge7-x\\\left|x+5\right|\ge x+5\end{matrix}\right.\)
\(\Rightarrow\left|7-x\right|+\left|x+5\right|\ge\left(7-x\right)+\left(x+5\right)\)
\(\Rightarrow\left|x-7\right|+\left|x+5\right|\ge12\)
\(\Rightarrow H\ge12\)
Dấu "=" xảy ra \(\Leftrightarrow\left\{{}\begin{matrix}7-x\ge0\\x+5\ge0\end{matrix}\right.\)
\(\Leftrightarrow\left\{{}\begin{matrix}x\le7\\x\ge-5\end{matrix}\right.\)
\(\Leftrightarrow-5\le x\le7\)
Vậy, MinH = 12 \(\Leftrightarrow-5\le x\le7\)
a) Ta có: \(A=2x^2-8x+10\)
\(=2\left(x^2-4x+5\right)\)
\(=2\left(x^2-4x+2^2+1\right)\)
\(2\left[\left(x-2\right)^2+1\right]\)
Ta lại có: \(\left(x-2\right)^2\ge0\)
\(\Rightarrow2\left[\left(x-2\right)^2+1\right]\ge2\)
\(\Rightarrow A\ge2\)
Dấu bằng xảy ra \(\Leftrightarrow\left(x-2\right)^2=0\)
\(\Leftrightarrow x-2=0\)
\(\Leftrightarrow x=2\)
Vậy MinA = 2 \(\Leftrightarrow x=2\)
Bạn nào cho mk 1 ik, mk cho bn ý 3 ik luôn. Mk hứa nếu nói dối bạn có thể Báo cáo sai phạm mk.
1. be => was / were
2. find => found
3. use => used
4. fall => fell
5. light => lit / lighted
6. escape => escaped
7. make => made
8. graze => grazed
9 , fit => fitted
10. lose=> lost
11. go => went
12. choose=> chose
13. appear => appeared
14. come => came
15. hold => held
16. break => broke
1. be => was / were
2. find => found
3. use => used
4. fall => fell
5. light => lit / lighted
6. escape => escaped
7. make => made
8. graze => grazed
9 , fit => fitted
10. lose=> lost
11. go => went
12. choose=> chose
13. appear => appeared
14. come => came
15. hold => held
16. break => broke
1. This is the first time he went abroad.
=> He hasn't went abroad.
2. She started driving 1 month ago
=> She hasn't drived for 1 month
3. We began eating when it started to rain
=> We have eaten since it started to rain
4. I last had my hair cut when I left her.
=> I haven't cut my hair since I left her.
5. The last time she kissed me was 5 months ago
=> She hasn't kissed me for 5 months.
6. It is a long time since we last met.
=> We haven't met for a long time
7. When did you have it?
=> How long have you had it?
8. This is the first time I had such a delicious meal.
=> I haven't had such a delicious meal.
9. I haven't seen him for 8 days
=> The last day I've seen him was 8 days ago.
10. I haven't taken a bath since Monday
=> It is Monday since I took a bath.
@Akai Haruma
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