Nhớ rằng: \(\frac{n}{a.\left(a+n\right)}=\frac{1}{a}+\frac{1}{a+n}\)
Ta có: \(A=\frac{1}{2}+\frac{1}{6}+\frac{1}{12}+...+\frac{1}{90}\)
\(A=\frac{1}{1.2}+\frac{1}{2.3}+\frac{1}{3.4}+...+\frac{1}{9.10}\)
Áp dụng công thức trên, ta có:
\(A=1-\frac{1}{2}+\frac{1}{2}-\frac{1}{3}+\frac{1}{3}-\frac{1}{4}+...+\frac{1}{9}-\frac{1}{10}\)
\(A=1-\frac{1}{10}=\frac{9}{10}\)
Tính tổng:
A=\(\frac{1}{2x4x6}\)+\(\frac{1}{4x6x8}\)+\(\frac{1}{6x8x10}\)+...+\(\frac{1}{22x24x26}\)
tính tổng : A = 1/2 + 5/6 + 11/12 + 19/20 + 29/30 + 41/42 + 55/56
On Internet now, people are arguing about this little math problem so I decided to post this:
Solve:
\(9-3\div\frac{1}{3}+1\)
A : 1/6 : 1/2 B 3 - 5/4
Bài 1 - Đặt tính rồi tính
15 423 : 9
306 427 : 23
706 999 : 201
7 406 x 2
36 200 x 206
9 731 x 27
Bài 2 - Tính giá trị của biểu thức
\(a,\) \(\dfrac{2}{5}\) + \(\dfrac{2}{7}\) x \(\dfrac{2}{3}\)
\(b,\) \(\dfrac{2}{6}\) : \(\dfrac{7}{5}\) + \(\dfrac{2}{6}\)
\(c,\) \((\) \(\dfrac{2}{3}\) - \(\dfrac{1}{6}\) \()\) x \(\dfrac{6}{7}\)
Giúp tớ nhé!!!!
1. Complete each number pattern by filling in the blanks with correct answers.
a) 1, 2, 4, 5, 7, 8, ( ), ( ),...
b) 3, 4, 7, 12, 19, (28), (39),...
c) 2, 3, 5, 8, 12, ( ), ( ),...
d) 2, 3, 5, 8, 13, ( ), ( ),...
2. A lesson starts at 8:10 am. It lasts for 1 hour 10 minutes. At what time does the lesson end?
3. Given that A and B are two different single digit numbers, find the values of A and B in each of the following.
a) A x A = 4 B b) A x B = 3 A
A = A =
B = B =
find a mistake.
1. He have breakfast at 7 o’clock.
A. have
B. at
2. He has lunch on 12 o’clock.
A. has
B. on
3. He get up at 6 o’clock .
A. get
B. at
4. Do he go home at 4:30?
A. Do
B. go
5. What does he get up ?
A. what
B. get up
I. Write the past participles of the following verbs.
1. eat => ………….... 6. decide => ………….... 11. travel => ………………
2. go => ………..….… 7. leave => ……………. 12. search => …………..….
3. write => ………..... 8. break => ……………. 13. visit => ………………..
4. clean => …………. 9. carry => ………….…. 14. do => …………..…..…
5. sell => ………...… 10. stay => …………..… 15. ride => ……………...
tính rồi rút gọn
a] 3/5 chia 3/4
b]1/4chia 1/2
