a/ 1/2 + 5/6 + 11/12 + 19/20
b/ 1/2 + 5/6 + 11/12 + 19/20 + 29/30 + 41/42
c/ (1-1/3) + (1-1/15) + (1-1/35) + (1-1/63)
d/ 1/2 + 5/6 + 11/12 + ... + 9899/9900
e/ 2/3 + 14/15 + 34/35 +62/63
f/ 2/3 + 14/15 + 34/35 + ... + 9998/9999
cái này tính cái gì thế
ko hiểu
Tìm A :
1 / A = ( 1 -\(\frac{1}{3}\)) + ( 1 - \(\frac{1}{15}\)) + ( 1 - \(\frac{1}{35}\)) + ( 1 - \(\frac{1}{63}\))
2 / A = ( 1 -\(\frac{1}{10}\)) + ( 1 - \(\frac{1}{40}\)) + ( 1 - \(\frac{1}{88}\)) + ( 1 - \(\frac{1}{154}\))
3 / A = \(\frac{2}{3}+\frac{14}{15}+\frac{34}{35}+....+\frac{9998}{9999}\)
4 / A = \(\frac{9}{10}+\frac{39}{40}+\frac{87}{88}+...+\frac{1119}{1120}\)
5 / A = \(\frac{9}{10}+\frac{39}{40}+\frac{87}{88}+\frac{153}{154}\)
Trình bày cách làm hộ mình nha ! Cảm ơn rất nhiều !
bạn ơi tách ra thừa số chung rồi làm như bình thường nha
1, A=\(\left(1+1+1+1\right)\)-\(\left(\frac{1}{3}+\frac{1}{15}+\frac{1}{35}+\frac{1}{63}\right)\)
=4-\(\left(\frac{1}{1.3}+\frac{1}{3.5}+\frac{1}{5.7}+\frac{1}{7.9}\right)\)
= 4-\(\left(\frac{1}{1}-\frac{1}{3}+...+\frac{1}{7}-\frac{1}{9}\right)\)
=4-\(\left(1-\frac{1}{9}\right)\)
= 4-\(\frac{8}{9}\)
= \(\frac{7}{9}\)
Câu 2 tương tự như câu 1
A=\(\left(1+1+1+1\right)\)-\(\left(\frac{1}{10}+\frac{1}{40}+...+\frac{1}{154}\right)\)
A= 4 -\(\left(\frac{1}{2.5}+\frac{1}{5.8}+...+\frac{1}{11.14}\right)\)
Bạn tự làm tiếp
Bài 3 Tính
a) A=1+1/2+1/2^2+1/2^3+...+1/2^99+1/2^100+1/2^101
b) B=1+1/3+1/3^2+1/3^3+...+1/3^100
c)1/2+5/6+11/12+19/20+29/30+41/42+55/56
d)2/3+14/15+34/35+...+9998/9999
e)1/2+5/6+11/12+...+9899/9900
Mình đang cần gấp bạn nào làm đúng mình cho 10 tick luôn giúp mình với huhuhu
Bài 3 Tính
a) A=1+1/2+1/2^2+1/2^3+...+1/2^99+1/2^100+1/2^101
b) B=1+1/3+1/3^2+1/3^3+...+1/3^100
c)1/2+5/6+11/12+19/20+29/30+41/42+55/56
d)2/3+14/15+34/35+...+9998/9999
e)1/2+5/6+11/12+...+9989/9990
Các bạn giúp mình với mình đang cần gấp lắm
Ai giúp mình làm bài này mình cho 10 tick luôn các bạn giúp mình với huhuhuhu
c)
\(\left(1-\frac{1}{2}\right)+\left(1-\frac{1}{6}\right)+....+\left(1-\frac{1}{42}\right)+\left(1-\frac{1}{56}\right)\)
\(\left(1+1+1+....+1+1\right)+\left(\frac{1}{1\times2}+\frac{1}{2\times3}+...+\frac{1}{6\times7}+\frac{1}{7\times8}\right)\)(Có 7 số 1)
\(7+1-\frac{1}{2}+\frac{1}{2}-\frac{1}{3}+\frac{1}{3}-\frac{1}{4}+....+\frac{1}{6}-\frac{1}{7}+\frac{1}{7}-\frac{1}{8}\)
\(7+1-\frac{1}{8}=\frac{63}{8}\)
Gợi ý 1 bài c) còn d) e) cũng làm như vậy nhé
Chúc bạn học tốt !!!
Tính nhanh :
a)13 – 12 + 11 + 10 – 9 + 8 – 7 – 6 + 5 – 4 + 3 + 2 – 1
b) 10/56 + 10/140 + 10/260 + ... + 10/2400
c) 1/1. 2. 3 + 1/2. 3. 4 + 1/3. 4. 5 + ... + 1/18. 19. 20
giup mik voi
B= 1/5 - 1/9 + 1/13 / 9/5 -1 + 9/13 + 10/7-10/11-10/17 / 12/7 - 12 /11 - 12/17
C=1/14 - 1/30 - 1/46 / 2/35 - 2/75 - 2/115 : 3/8 - 15/17 + 30/31 / 1/6 - 20/51 + 40/93
D= 1/100.99 - 1/99.98 - 1/98.97 - ........... - 1/3.2 - 1/2.1
E= ( 1+2+3+.......+100) . ( 1/3-1/5-1/7-1/9) . ( 6,3 .12 - 21 .3,6) / 1/2+1/3+1/4+..........+ 1/100
Nguyễn Đăng Duy ơi bài trên là tính nhanh hay tính vậy bạn .
Bài làm (không chắc)
B=1/5-1/9+1/13 / 9/5-1+9/13 + 10/7-10/11-10/17 / 12/7-12/11-12/17
=1/5:9/5-1/9:1+1/13:9/13 + 10/7:12/7-10/11:12/11-10/17:12/17
=1/9-1/9+1/9 + 5/6-5/6-5/6
=1/9-5/6
=39/54=13/18
1+2+3+4+5+6+7+8+9+10+11+12+13+14+15+16+17+18+19+20+21+22+23+24+25+26+27+28+29+30+31+32+33+34+35+36+37+38+39+40+41+42+43+44+45+46+47+48+49+50+51+52+53+54+56+57+58+59+60+61+62+63+64+65+66+67+68+69+70=?
bài 1
4/7+4
3+6/11
3-5/7
21/9-2
15/24+2
63/45-20/25
3/4-2/8
6/7-5/8
37/45-5/9
46/39-11/13
5/12+3/4+1/3
1/2+3/7+11/14
7/10-(1/5+1/4)
15/4-2/3-3/4
`4/7+4`
`=4/7+4/1`
`=4/7+28/7`
`=32/7`
__
`3+6/11`
`=33/11+6/11`
`=39/11`
__
`3-5/7`
`=3/1-5/7`
`=21/7-5/7`
`=16/7`
__
`21/9-2`
`=21/9-18/9`
`=3/9`
`=1/3`
__
`15/24+2`
`=15/24+48/24`
`=63/24`
`=21/16`
__
`63/45-20/25`
`=63/45-4/5`
`=63/45-36/45`
`=27/45`
`=9/15`
__
`3/4-2/8`
`=3/4-1/4`
`=2/4`
__
`6/7-5/8`
`=48/56-35/56`
`=13/56`
__
`37/45-5/9`
`=37/45-25/45`
`=12/45`
`=4/15`
__
`46/39-11/13`
`=46/39-33/39`
`=13/39`
`=1/2`
__
`5/12+3/4+1/3`
`=5/12+9/12+4/12`
`=14/12+4/12`
`=18/12`
`=3/2`
__
`1/2+3/7+11/14`
`=7/14+6/14+11/14`
`=13/14+11/14`
`=24/14`
`=12/7`
__
`7/10-(1/5+1/4)`
`=7/10-(4/20+5/20)`
`=7/10-9/20`
`=14/20-9/20`
`=5/20`
`=1/4`
__
`15/4-2/3-3/4`
`=(15/4-3/4)-2/3`
`=12/4-2/3`
`=3-2/3`
`=9/3-2/3`
`=7/3`
