Giải phương trình \(\sqrt{x+2-3\sqrt{2x-5}}+\sqrt{x-2+\sqrt{2x-5}}=2\sqrt{2}\)
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15 tháng 2 2022
Gọi chiều dài chiều rộng thửa ruộng lần lượt a ; b ( a > b> 0 )
Theo bài ra ta có hpt \(\hept{\begin{cases}2\left(a+b\right)=100\\\left(a+5\right)\left(b-2\right)=ab+30\end{cases}\Leftrightarrow\hept{\begin{cases}a+b=50\\-2a+5b=40\end{cases}\Leftrightarrow}\hept{\begin{cases}a=30\\b=20\end{cases}}}\)(tm)
Vậy chiều dài ban đầu là 30 m
chiều rộng ban đầu là 20 m
14 tháng 2 2022
VIII. Give the correct form of verbs.
1.They have lived in London since 1980 . (live)
2.She has worked here for two years. (work)
3. Does John do this job ? (do)
4.They don't live in Hanoi from 1970 to 1999 ( not live)
5. Did you put your book on my desk last night ? (put)
6.He is studying English at this school now. (study)
7.Our present teacher s living in this city . (live)
8.Nobody lives in those houses. They have been empty for many years (be)
9.Cindy is in her office. She works (work) until 7 o'clock.
10. My sister came to see my last night (come)
LM
11 tháng 3 2022
1. Where are they planting the trees?
2. When will she visit Ha Noi?
3. When does she often watch TV?
4. How often do we go to school?
5. What are Tom and Mai doing?
6. How are all the buildings in London?
7. How is it in Sweden in the winter?
8. Where was your father last month?
9. Why did she go to the doctor?
10. When did Nam left home yesterday?
11. Where will your future house be?
12. How often does she go to the fitness centre.
13. When did they join the environment project?
14. What does our class have on Monday?
15. Where will we travel to by a super car?
14 tháng 2 2022
1 She s reading books.
2 He lives far from the school.
3 They might have robots to do their housework in the future.
4 No lake in Ha Noi is larger than West Lake
Đúng thì k mình nhé.Chúc bạn học tốt
14 tháng 2 2022
1.She is interested in reading books..
She s …reading books……………
2.We live near the school, but he doesn’t.
He lives ....far the school..............................................................................................................
3.They will probably have robots to do their housework in the future.
They might................have robots to do their housework in the future................................................................................................
4. The West Lake is the largest one in Ha Noi.
No lake in Ha Noi is larger than West Lake./ No lake in Ha Noi is as large as West Lake.
ĐK: \(x\ge\frac{5}{2}\).
\(\sqrt{x+2-3\sqrt{2x-5}}+\sqrt{x-2+\sqrt{2x-5}}=2\sqrt{2}\)
\(\Leftrightarrow\sqrt{2x+4-6\sqrt{2x-5}}+\sqrt{2x-4+2\sqrt{2x-5}}=4\)
\(\Leftrightarrow\sqrt{2x-5-2.3.\sqrt{2x-5}+9}+\sqrt{2x-5+2.1.\sqrt{2x-5}+1}=4\)
\(\Leftrightarrow\sqrt{\left(\sqrt{2x-5}-3\right)^2}+\sqrt{\left(\sqrt{2x-5}+1\right)^2}=4\)
\(\Leftrightarrow\left|\sqrt{2x-5}-3\right|+\left|\sqrt{2x-5}+1\right|=4\)(1)
Nếu \(\sqrt{2x-5}\ge3\Leftrightarrow x\ge7\): (1) tương đương với:
\(\sqrt{2x-5}-3+\sqrt{2x-5}+1=4\)
\(\Leftrightarrow\sqrt{2x-5}=3\Leftrightarrow x=7\)(thỏa mãn)
Nếu \(\sqrt{2x-5}< 3\Leftrightarrow\frac{5}{2}\le x< 7\): (1) tương đương với:
\(3-\sqrt{2x-5}+\sqrt{2x-5}+1=4\)
\(\Leftrightarrow4=4\)(luôn đúng)
Vậy phương trình có nghiệm là \(\frac{5}{2}\le x\le7\).