b)C=1+4(99+3)49/2+97.99.101.103/8
Tinh a)B=(1+4.3+4.5+..+4.99)(1.3.5+3.5.7+...+97.99.100)
Những câu hỏi liên quan
Tính tổng
a) 9+99+999+...+999999
b) 1+11+111+...+1111111
c)1.2 + 2.3+3.4+4.5+...+98.99
d) 1.3.5 + 3.5.7+5.7.9+...+95.97.99
a) 9 + 99 + 999 + ... + 999999
= (10 - 1) + (100 - 1) + (1000 - 1) + ... + (1000000 - 1)
= (101 + 102 + 103 + ... + 106) - (1.6)
= 1111110 - 6 = 1111104
b) 1 + 11 + 111 + ... + 1111111
= 1 + (101 + 1) + (102 + 101 + 1) + ... + (106 + 105 + 104 + 103 + 102 + 101 + 1)
= 101 . 6 + 102 . 5 + 103 . 4 + ... + 106. 1) + (1 + 1.6)
= 60 + 500 + 4000 + ... + 1000000 + 7
= 1234560 + 7 = 1234567
c) C = 1.2 + 2.3 + 3.4 + 4.5 + ... + 98.99
3C = 1.2.3 + 2.3.3 + 3.4.3 + 4.5.3 + ... + 98.99.3
3C = 1.2.3 + 2.3.(4 - 1) + 3.4.(5 - 2) + ... + 98.99.(100 - 97)
3C = 1.2.3 + 2.3.4 - 2.3.1 + 3.4.5 - 3.4.2 +...+ 98.99.100 - 98.99.97
3C = 98.99.100
C = \(\dfrac{98.99.100}{3}\) = 323400
d) D = 1.3.5 + 3.5.7 + 5.7.9 + ... + 95.97.99
8D = 1.3.5.8 + 3.5.7.8 + 5.7.9.8 + ... + 95.97.99.8
8D = 1.3.5.(7 + 1) + 3.5.7.(9 - 1) + 5.7.9.(11 - 3) + ... + 95.97.99.(101 - 93)
8D = 1.3.5.7 + 1.3.5.1 + 3.5.7.9 - 3.5.7.1 + 5.7.9.11 - 5.7.9.3 + ... + 95.97.99.101 - 95.97.99.93
8D = 1.3.5.1 + 95.97.99.101
D = \(\dfrac{1.3.5.1+95.97.99.101}{8}=15517600\)
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Tính:
a)1^2+2^2-3^2+4^2-.........-19^2+20^2
b)1.2.3+3.4.5+......99.100.101
c)1.3.5+3.5.7+......+95.97.99
d)9+99+999+............+99...9(10 số 9)
Tính.
a)A=1/1.3.5+1/3.5.7+1/5.7.9+...+1/97.99.101
b)B=2^2019-2^2018-2^2017-...-2+1
c)C=1/1.2+1/3.4+...+1/49.50-1/50-1/49-...-1_2
d)D=1/2!+5/3!+11/4!+..+99.100-1/100!
15 tháng 4 2023 lúc 13:47
a) dfrac{2}{1.2.3}+dfrac{2}{2.3.4}+dfrac{2}{3.4.5}+...+dfrac{2}{18.19.20}b) dfrac{4}{1.3.5}+dfrac{4}{3.5.7}+dfrac{4}{5.7.9}+...+dfrac{4}{21.23.25}c) dfrac{3}{1.2}-dfrac{5}{2.3}+dfrac{7}{3.4}-dfrac{9}{4.5}+...+dfrac{39}{19.20}-dfrac{41}{20.21}d) dfrac{8}{9}cdotdfrac{15}{16}cdotdfrac{24}{25}cdot...cdotdfrac{99}{100}cdotdfrac{120}{121}e) left(1+dfrac{7}{9}right)left(1+dfrac{7}{20}right)left(1+dfrac{7}{33}right)left(1+dfrac{7}{48}right)...left(1+dfrac{7}{180}right)Các bạn không nhất thiết phải làm h...
Đọc tiếp
a) \(\dfrac{2}{1.2.3}+\dfrac{2}{2.3.4}+\dfrac{2}{3.4.5}+...+\dfrac{2}{18.19.20}\)
b) \(\dfrac{4}{1.3.5}+\dfrac{4}{3.5.7}+\dfrac{4}{5.7.9}+...+\dfrac{4}{21.23.25}\)
c) \(\dfrac{3}{1.2}-\dfrac{5}{2.3}+\dfrac{7}{3.4}-\dfrac{9}{4.5}+...+\dfrac{39}{19.20}-\dfrac{41}{20.21}\)
d) \(\dfrac{8}{9}\cdot\dfrac{15}{16}\cdot\dfrac{24}{25}\cdot...\cdot\dfrac{99}{100}\cdot\dfrac{120}{121}\)
e) \(\left(1+\dfrac{7}{9}\right)\left(1+\dfrac{7}{20}\right)\left(1+\dfrac{7}{33}\right)\left(1+\dfrac{7}{48}\right)...\left(1+\dfrac{7}{180}\right)\)
Các bạn không nhất thiết phải làm hết, làm cho nó dễ hiểu được thì càng tốt để mk vận dụng
a: \(=\dfrac{1}{1\cdot2}-\dfrac{1}{2\cdot3}+\dfrac{1}{2\cdot3}-\dfrac{1}{3\cdot4}+...+\dfrac{1}{18\cdot19}-\dfrac{1}{19\cdot20}\)
=1/2-1/380
=179/380
b: \(=\dfrac{1}{1\cdot3}-\dfrac{1}{3\cdot5}+\dfrac{1}{3\cdot5}-\dfrac{1}{5\cdot7}+...+\dfrac{1}{21\cdot23}-\dfrac{1}{23\cdot25}\)
\(=\dfrac{1}{3}-\dfrac{1}{575}=\dfrac{572}{1725}\)
c: \(=1+\dfrac{1}{2}-\dfrac{1}{2}-\dfrac{1}{3}+...+\dfrac{1}{19}+\dfrac{1}{20}-\dfrac{1}{20}-\dfrac{1}{21}\)
=1-1/21
=20/21
d: \(=\left(1-\dfrac{1}{9}\right)\left(1-\dfrac{1}{16}\right)\cdot...\cdot\left(1-\dfrac{1}{121}\right)\)
\(=\dfrac{2}{3}\cdot\dfrac{3}{4}\cdot...\cdot\dfrac{10}{11}\cdot\dfrac{3}{2}\cdot\dfrac{4}{3}\cdot...\cdot\dfrac{12}{11}\)
\(=\dfrac{2}{11}\cdot\dfrac{12}{2}=\dfrac{12}{11}\)
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Giup mk .Mk like bn nào trả lời sóm nhất , đúng nhất .A6/1.3.7 + 6/3.7.9 + 6/7.9.13 + 6/9.13.15 + 6/13.15.19Nếu các bn ko biết giải cách tiểu học thì giải theo sauB4/1.3.5 + 4/3.5.7 + 4/5.7.9 + 4/7.9.11 + 4/9.11.13B5-1/1.3.5 + 7-3/3.5.7 +........+ 13-9/9.11.13B5/1.3.5 - 1/1.3.5 + 7/3.5.7 - 3/3.5.7 +............... + 13/9.11.13 - 9/9.11.13B1/1.3 - 1/3.5 + 1/3.5 - 1/5.7 + ............. + 1/9.11 - 1/11.13B1/1.3-1/11.13B 11.13/3.11.13 - 3/3.11.13 140/425
Đọc tiếp
Giup mk .Mk like bn nào trả lời sóm nhất , đúng nhất .
A=6/1.3.7 + 6/3.7.9 + 6/7.9.13 + 6/9.13.15 + 6/13.15.19
Nếu các bn ko biết giải cách tiểu học thì giải theo sau
B=4/1.3.5 + 4/3.5.7 + 4/5.7.9 + 4/7.9.11 + 4/9.11.13
B=5-1/1.3.5 + 7-3/3.5.7 +........+ 13-9/9.11.13
B=5/1.3.5 - 1/1.3.5 + 7/3.5.7 - 3/3.5.7 +............... + 13/9.11.13 - 9/9.11.13
B=1/1.3 - 1/3.5 + 1/3.5 - 1/5.7 + ............. + 1/9.11 - 1/11.13
B=1/1.3-1/11.13
B= 11.13/3.11.13 - 3/3.11.13 = 140/425
1) tính :
a) 2/ 1.2.3 + 2/ 2.3.4 + ...+ 2/ 98.99.100
b) 4/ 2.4.6 + 4/ 4.6.8 + ...+ 4/ 50.52.54
c) 8/ 1.3.5 + 8/ 3.5.7 + ...+ 8/ 18.19.20
d) 1/ 1.2.3 + 1/ 2.3.4 + ... + 1/ 18.19.20
A6/1.3.7 + 6/3.7.9 + 6/7.9.13 + 6/9.13.15 + 6/13/15/19Giup mk nhé và làm theo cách dưới :C4/1.3.5 + 4/3.5.7 + 4/5.7.9 + 4/7.9.11 + 4/9.11.13C5-1/1.3.5 + 7-3 /3.5.9 + ............................ + 13-9/9.11.13C5/1.3.5 - 1/1.3.5 + 7/3.5.7 - 3/3.5.7 + ................... + 13/9.11.13 - 9/9.11.13C1/1.3 -1/3.5 + 1/3.5- 1/5.7 + ................................. + 1/9.11 - 1/11.13C1/1.3 - 1/11.13C 11.13/3.11.13 - 3/3.11.13 C140/425
Đọc tiếp
A=6/1.3.7 + 6/3.7.9 + 6/7.9.13 + 6/9.13.15 + 6/13/15/19
Giup mk nhé và làm theo cách dưới :
C=4/1.3.5 + 4/3.5.7 + 4/5.7.9 + 4/7.9.11 + 4/9.11.13
C=5-1/1.3.5 + 7-3 /3.5.9 + ............................ + 13-9/9.11.13
C=5/1.3.5 - 1/1.3.5 + 7/3.5.7 - 3/3.5.7 + ................... + 13/9.11.13 - 9/9.11.13
C=1/1.3 -1/3.5 + 1/3.5- 1/5.7 + ................................. + 1/9.11 - 1/11.13
C=1/1.3 - 1/11.13
C= 11.13/3.11.13 - 3/3.11.13
C=140/425
mình cũng ko hiểu cách giải này cho lắm nên mình làm thế thôi
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Bài 1:Tính hợp lí các tổng sau:A 1/3+1/32+1/33+ ... +1/3100B 1+2+22+23+...+22009 / 1 - 22010C 12/1.3.5 + 12/3.5.7 + ... + 12/25.27.29D 1+1/2 + 1/4 + 1/8 + .... + 1/1024Bài 2:Tìm x,biết:a) 3/2 . x - 70+10/11 : (131313/151515 + 131313/353535 + 131313/636363 + 131313/999999) - 5b) ( 1 / 1.101 + 1 / 2.102 + ... + 1 / 10.110).x 1 / 1.11 + 1 / 2.12 + ... + 1 / 100.110c) Chứng tỏ rằng: 49/100 S 1/22 + 1/32+...+1/992 1
Đọc tiếp
Bài 1:Tính hợp lí các tổng sau:
A = 1/3+1/32+1/33+ ... +1/3100
B = 1+2+22+23+...+22009 / 1 - 22010
C = 12/1.3.5 + 12/3.5.7 + ... + 12/25.27.29
D = 1+1/2 + 1/4 + 1/8 + .... + 1/1024
Bài 2:Tìm x,biết:
a) 3/2 . x - 70+10/11 : (131313/151515 + 131313/353535 + 131313/636363 + 131313/999999) = - 5
b) ( 1 / 1.101 + 1 / 2.102 + ... + 1 / 10.110).x = 1 / 1.11 + 1 / 2.12 + ... + 1 / 100.110
c) Chứng tỏ rằng: 49/100 < S = 1/22 + 1/32+...+1/992 <1
1. rút gọn rồi quy đồng mẫu các phân số
a. \(\dfrac{4.5+4.11}{8.7+4.3}\), \(\dfrac{-15.8+10.7}{5.6+20.3}\)và\(\dfrac{2^4.5^2.7}{2^3.5.7^2.11}\)
a: \(\dfrac{4\cdot5+4\cdot11}{8\cdot7+4\cdot3}=\dfrac{20+44}{56+12}=\dfrac{64}{68}=\dfrac{16}{17}=\dfrac{11088}{11781}\)
\(\dfrac{-15\cdot8+10\cdot7}{5\cdot6+20\cdot3}=\dfrac{-120+70}{30+60}=\dfrac{-50}{90}=\dfrac{-5}{9}=\dfrac{-6545}{11781}\)
\(\dfrac{2^4\cdot5^2\cdot7}{2^3\cdot5\cdot7^2\cdot11}=\dfrac{2\cdot5}{7\cdot11}=\dfrac{10}{77}=\dfrac{1530}{11781}\)
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