2^3 + 3^3 =
CL
Những câu hỏi liên quan
Tính giá trị biểu thức
a, A = (1 - 1/1+2) . (1 - 1/1+2+3) . (1- 1/1+2+3+4) . ... .(1- 1/1+2+...+100)
b, B = (2/3+ 3/4 +...+99/100).(1/2+2/3+...+98/99) - (1/2+2/3+...+99/100).(2/3+3/4+...+98/99)
c, C = \(\frac{3^3+1^3}{2^3-1^3}+\frac{5^3+2^3}{3^3-2^3}+\frac{7^3+3^3}{4^3-3^3}+...+\frac{41^3+20^3}{21^3-20^3}\)
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Chứng minh rằng:
a) A=1/3+1/(3^2)+1/(3^3)+...+1/(3^99)<1/2
b) B=3/(1^2*2^2)+5/(2^2*3^2)+7/(3^2*4^2)+...+19/(9^2*10^2)<1
c) C=1/3+2/(3^2)+3/(3^3)+4/(3^4)+...+100/(3^100)<3/4
a; ( 2+2^2+2^3+........+2^60) chia hết cho 3; 7; 15
b; (1+3+3^2+3^3+......+3^1991) chia hết cho 13; 41
c; ( 3+3^2+3^3+........+3^1998) chia hết cho 12; 39
3/1+3/1+2 3/1+2+3+3/1+2+3+4+3/1+2+3+4+5+....+3/1+2+3+4..+99
a, Cho biết: \(1^2+2^2+3^2+...+10^2=385\)
Tính A= \(3^2+6^2+9^2+...+30^2\)
b, Cho biết: \(1^3+2^3+3^3+...+10^3=3025\)
Tính B= \(2^3+4^3+6^3+...+20^3\)
a: A=3^2(1^2+2^2+...+10^2)
=9*385
=3465
b: B=2^3(1^3+2^3+...+10^3)
=8*3025
=24200
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Ngu như con chó thế. Mỗi bài cỏn con này mà ko giải được! ngu vãi lồn. Đúng là cha mẹ nuôi ăn tốn cơm, tốn gạo
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TA
8 tháng 8 2023 lúc 11:24
A=1-2-2^3-2^3+2^4-...+2^2022B=1+3+3^2+3^3+3^4+...+3^2022
Xem chi tiết
A= 1 - 2 - 22 - 23 + 24 +...+ 22022 (sửa đề)
= -13 + (24 + 25 + 26 + ... + 22022)
2A = -26 + (25 + 26 + 27 + ... + 22023)
2A - A = -26 + (25 + 26 + 27 + ... + 22023) - [-13 + (24 + 25 + 26 + ... + 22022)]
A = -13 +(22023 - 24)
= 22023 - 29
Vậy...
B = 1 + 3 + 32 + 33 + 34 + ... + 32022
3B = 3 + 32 + 33 + 34 + 35 +...+ 32023
3B - B = 3 + 32 + 33 + 34 + 35 +...+ 32023 - (1 + 3 + 32 + 33 + 34 + ... + 32022)
2B = 32023 - 1
=> B = \(\dfrac{3^{2023}-1}{2}\)
Vậy...
#Ayumu
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bài 3:
a) x - 3/4 = 6 x 3/8 b) 7/8 : x = 3 - 1/2 c) x + 1/2 x 1/3 = 3/4
d) 3/2 x 4/5 - x = 2/3 e) X x 3 1/3 = 3 1/3 : 4 1/4 f) 5 2/3 : x = 3 2/3 - 2 1/2
a) \(x-\dfrac{3}{4}=6\times\dfrac{3}{8}\)
\(x-\dfrac{3}{4}=\dfrac{9}{4}\)
=> \(x=\dfrac{9}{4}+\dfrac{3}{4}=3\)
b) \(\dfrac{7}{8}:x=3-\dfrac{1}{2}\)
\(\dfrac{7}{8}:x=\dfrac{5}{2}\)
=> \(x=\dfrac{7}{8}:\dfrac{5}{2}=\dfrac{7}{20}\)
c) \(x+\dfrac{1}{2}\times\dfrac{1}{3}=\dfrac{3}{4}\)
\(x+\dfrac{1}{6}=\dfrac{3}{4}\)
=> \(x=\dfrac{3}{4}-\dfrac{1}{6}=\dfrac{7}{12}\)
d) \(\dfrac{3}{2}\times\dfrac{4}{5}-x=\dfrac{2}{3}\)
\(\dfrac{6}{5}-x=\dfrac{2}{3}\)
=> \(x=\dfrac{6}{5}-\dfrac{2}{3}=\dfrac{8}{15}\)
e) \(x\times3\dfrac{1}{3}=3\dfrac{1}{3}:4\dfrac{1}{4}\)(?)
\(x\times\dfrac{10}{3}=\dfrac{40}{51}\)
=> \(x=\dfrac{40}{51}:\dfrac{10}{3}=\dfrac{4}{17}\)
f) \(5\dfrac{2}{3}:x=3\dfrac{2}{3}-2\)
\(\dfrac{17}{3}:x=\dfrac{5}{3}\)
=> \(x=\dfrac{17}{3}:\dfrac{5}{3}=\dfrac{17}{5}\)
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a: =>x-3/4=18/8=9/4
=>x=9/4+3/4=12/4=3
b: =>7/8:x=5/2
=>x=7/8:5/2=7/8*2/5=14/40=7/20
c: x+1/2*1/3=3/4
=>x+1/6=3/4
=>x=3/4-1/6=9/12-2/12=7/12
d: =>12/10-x=2/3
=>6/5-x=2/3
=>x=6/5-2/3=18/15-10/15=8/15
e: =>x*10/3=10/3:17/4=10/3*4/17
=>x=4/17
f: =>17/3:x=13/3-5/2=26/6-15/6=11/6
=>x=17/3:11/6=17/3*6/11=34/11
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LL
23 tháng 8 2023 lúc 20:33
5) (3-1/4+2/3) - (5-1/3-6/5) - (6-7/4+3/2) 6) (6-2/3+1/2) - (5+5/3-3/2)-(3-7/3+5/2)
7) (5/3-3/7+9)-(2+5/7-2/3)+(8/7-4/3-10) 8) (8-9/4+2/7)-(-6-3/7+5/4)-(3+2/4-9/7 pls help me
5: \(=3-\dfrac{1}{4}+\dfrac{2}{3}-5+\dfrac{1}{3}+\dfrac{6}{5}-6+\dfrac{7}{4}-\dfrac{3}{2}\)
\(=3-5-6+\dfrac{-1}{4}+\dfrac{7}{4}+\dfrac{2}{3}+\dfrac{1}{3}+\dfrac{6}{5}-\dfrac{3}{2}\)
\(=-8+\dfrac{3}{2}+1+\dfrac{-3}{10}\)
\(=-7+\dfrac{15-3}{10}=-7+\dfrac{6}{5}=-\dfrac{29}{5}\)
6: \(=6-\dfrac{2}{3}+\dfrac{1}{2}-5-\dfrac{5}{3}+\dfrac{3}{2}-3+\dfrac{7}{3}-\dfrac{5}{2}\)
\(=6-5-3-\dfrac{2}{3}-\dfrac{5}{3}+\dfrac{7}{3}+\dfrac{1}{2}+\dfrac{3}{2}-\dfrac{5}{2}\)
\(=-2-\dfrac{1}{2}=-\dfrac{5}{2}\)
7: \(=\dfrac{5}{3}-\dfrac{3}{7}+9-2-\dfrac{5}{7}+\dfrac{2}{3}+\dfrac{8}{7}-\dfrac{4}{3}-10\)
\(=9-2-10+\dfrac{5}{3}+\dfrac{2}{3}-\dfrac{4}{3}+\dfrac{-3}{7}-\dfrac{5}{7}+\dfrac{8}{7}\)
=-3+1
=-2
8: \(=8-\dfrac{9}{4}+\dfrac{2}{7}+6+\dfrac{3}{7}-\dfrac{5}{4}-3-\dfrac{2}{4}+\dfrac{9}{7}\)
\(=8+6-3+\dfrac{2}{7}+\dfrac{3}{7}+\dfrac{9}{7}-1-\dfrac{2}{4}\)
\(=11+2-1-\dfrac{1}{2}\)
=11+1/2
=11,5
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LL
23 tháng 8 2023 lúc 20:58
(3-1/4+2/3) - (5-1/3-6/5) - (6-7/4+3/2) (6-2/3+1/2) - (5+5/3-3/2)-(3-7/3+5/2)
(5/3-3/7+9)-(2+5/7-2/3)+(8/7-4/3-10) (8-9/4+2/7)-(-6-3/7+5/4)-(3+2/4-9/7 )
mọi người ơi giúp mik với ạ
Cho D=2^3/3^3+2^3/5^3+2^3/7^3+...+2^3/2013^3
so sánh D với 2/3
Gợi ý :D=2*(2^2/3^3+2^2/5^3+...+2^2/2013^3)
=2*(4/3^3+4/5^3+...+4/2013^3)
Ta có 4/3^3=4/3.3.3<4/1.3.5=1/1.3-1/3.5
...
2(4/3^3+4/5^3+...+4/2013^3)<2(4/1.3.5+4/3.5.7+...+4/2011.2013.2015)
Mình mới làm đến đó thôi mong bạn thông cảm nha
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