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\(\frac{1}{2\cdot3}+\frac{1}{3\cdot4}+\frac{1}{4\cdot5}+...+\frac{1}{38\cdot39}+\frac{1}{39.40}\)
\(=\frac{1}{2}-\frac{1}{3}+\frac{1}{3}-\frac{1}{4}+...+\frac{1}{38}-\frac{1}{39}+\frac{1}{39}-\frac{1}{40}\)
\(\frac{1}{2}-\frac{1}{40}\)
= 0,475
1. Her name is Hoa
2. She get up at six o'clock
3. She has breakfast
4. Her class start at seven o'clock
5. No, she doesn't
1, Don't play with that sharp knife.
2, What does your brother do in his free time?
3, the hare fell asleep on the road.
4. turn right at the next corner.
5. i went to Phu Quoc Island.
6. Minh would to be a pilot because he'd to fly planes.
7 Mr Kiet should take a rest.
8 Quan went to the doctor because he had a headache.
9. Tam was beautiful and gentle.
10. My grandma often works in the garden in her free time.
11. What are you doing with the stove?
12 You shouldn't eat ice cream.
13 What would you likae to be in the future?
\(\overline{ab}x15=\overline{7ab}< =>\overline{ab}x15=700+\overline{ab}< =>14x\overline{ab}=700\)
=>\(\overline{ab}=700:14=50\)
29,15
This number is:
29,15