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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.
X. Complete the sentences with the past simple or past continuous form of the verbs in brackets.
11. He _was walking_(walk) down the road when he ____heard____(hear) a loud noise.
12. When we _were___(be) in Canana, we _went__(go) skiing almost every day.
13. Where _did__ you __go_(go) last summer holiday, Jim? ~ Well, I _took__(take) a trip to Minneapolis.
14. When I __arrived___(arrive), they ____said____(say) hello but continued working.
15. When you _______met__(meet) me yesterday, I __didn't go___(not go) to school, I ___went__(go) to the doctor’s - I felt terrible.
1. How much does this dictionary cost ?
2. Where did she buy it ?
3.Where is the bank ?
4. When did you saw her ?
5. Who bought a poster ?
6. Where was your father last month ?
7. what's your favorite subject ?
8. what do you do in your free time?
9. what is your mother doing at the moment ?
10 . how often do you go to the cinema ?
11. when do they go to the beach ?
12. what did they see at the zoo ?
13. why does the teacher angry ?
14. How many kilos of oranges did you buy?
15. Where does Nga's father work?
16. What does his mother do every day ?
Mik mất công làm cho bn mong bạn đừng seen xem chùa ạ