1 tấm vải dài là :

90 : 5 = 18 ( m )

13 tấm vải dài là :

18 x 13 = 234 ( m )

Đáp số : 234 m

Mk làm nhầm, 2. b nhé

1) Tính:

\(\frac{1}{100.99}-\frac{1}{99.98}-\frac{1}{98.97}-....-\frac{1}{3.2}\)\(-\frac{1}{2.1}\)

\(=\frac{1}{100}-\frac{1}{99}-\frac{1}{99}-\frac{1}{98}-\frac{1}{98}-\frac{1}{97}-\)\(...-\frac{1}{3}-\frac{1}{2}-\frac{1}{2}-\frac{1}{1}\)

\(=\frac{1}{100}-\frac{1}{1}\)

\(=-\frac{99}{100}\)

Give the correct tense of the verb in brackets:

1. What .............. you (do) ........... at that time last week?

2. Yesterday while I (water) .................. the garden, it (begin) ............. to rain.

3. They (not speak) .................. to each other since they quarreled.

4. Up to now, I (do) .................. every exercise in this book.

5. Mrs. Green (take) ................ Alice to the dentist ' s many times.

6. I (not get) ................... up until 8 o ' clock yesterday morning.

7. She (stay) ............. with her parents at the moment thought she (have) ................ her own flat.

8. As I (cross) .............. the road I (step) .............. on a banana skin and (fall) ............. heavily.

9. The old man (fall) ................ as he (get) ................. into the bus.

10. What ............. you (do) ................ between 9:00 and 10:00 yesterday?

11. This time last year they (visit) .............. Ha Long Bay.

12. It (be) .............. hours since he left.

13. Some animals (not eat) .............. during the winter.

14. I think he (leave) ................... as soon as he knows the news.

15. She hopes it (not rain) ............... when they start early tomorrow.

16. If I (lose) ............ my licence, I shall lose my job.

17. How many films .............. you (see) ............. this month?

18. Leave a note for them on the table and they (see) .............. it when they come.

19. I ' ve decided to repaint this room.-Oh, have you? What color ............. you (paint) ................?

20. I'm going away for a few days. I (phone) ................ you when I get back.

Tìm nghiệm của các đa thức sau:

a) x⁴ + 8x

b) (2 + x)(8 - 6x)

Bài 1:

a) 4x² +9x +5

b) x² + 8x +15

c) -x⁴ + 4x³ + 9

d) -4x⁴ + 2x³ + 2x² - 8x + 7