BÀI TÍNH NHANH
A.2/3+2/6+2/12+2/24+2/48+2/96+2/192
B.1/2+1/4+1/8+1/16+1/32+1/64+1/128+1/256
C.1/3+1/9+1/27+1/81+1/243+1/729
D.3/2+3/8+3/32+3/128+3/512
E.3+3/5+3/25+3/125+3/625
tính nhanh :Bài 1: 1/3+1/9+1/27+1/81+1/243+1/729
Bài 2 : 1+5/4+5/8+5/16+5/32+5/64
Bài 3: 3/2+3/8+3/32+3/128+3/512
Bài 4: 3+3/5+3/25+3/125+3/625
Bài 5: 1/5+1/10+1/20+1/40+.........+1/1280
Bài 6: 1/3+1/9+1/27+1/81+.............+1/59049
Mk mong các bn giúp đỡ hãy lm đúng cho mk nha~mk cần rất gấp sáng mai rùi nha~
Bài 1: 1/3+1/9+1/27+1/81+1/243+1/729
Đặt:
A = 1 + 1/3 + 1/9 + 1/27 + 1/81 + 1/243 + 1/729
Nhân A với 3 ta có:
\(Ax3=3+\frac{1}{3}+\frac{1}{9}+\frac{1}{27}+\frac{1}{81}+\frac{1}{243}\)
\(\Rightarrow Ax3-S=3-\frac{1}{243}\)
\(\Rightarrow2A=\frac{2186}{729}\)
\(\Rightarrow A=\frac{2186}{729}:2\)
\(\Rightarrow A=\frac{1093}{729}\)
Bài 2Câu hỏi của nguyễn phạm mimi - Toán lớp 6 | Học trực tuyến
Bài 3
nguồn:Tính nhanh: 3/2 + 3/8 + 3/32 + 3/128 + 3/512
Bài 4Câu hỏi của VŨ THỊ MAI CA - Toán lớp 4 - Học toán với OnlineMath
Bài 5Câu hỏi của Phạm Dora - Toán lớp 4 - Học toán với OnlineMath
Bài 6 Câu hỏi của huỳnh thị thu uyên - Toán lớp 5 - Học toán với OnlineMath
tính nhanh p/s 1+ 5/4 + 5/8 + 5/16 + 5/32 + 5/64
b) 1/3 +1/9 + 1/27 + 1/81 +...........+ 1/59049
c) 3/2 + 3/8 + 3/32 +3/128 + 3/512
d) 1/2 + 1/4 + 1/8 + 1/16 + 1/32 + 1/64 + 1/128 + 1/256 giúp mình với
b: A=1/3+1/9+...+1/3^10
=>3A=1+1/3+...+1/3^9
=>A*2=1-1/3^10=(3^10-1)/3^10
=>A=(3^10-1)/(2*3^10)
c: C=3/2+3/8+3/32+3/128+3/512
=>4C=6+3/2+...+3/128
=>3C=6-3/512
=>C=1023/512
d: A=1/2+...+1/256
=>2A=1+1/2+...+1/128
=>A=1-1/256=255/256
a) \(\frac{1}{2}+\frac{1}{4}+\frac{1}{8}+\frac{1}{16}+\frac{1}{32}+\frac{1}{64}\) b) \(\frac{1}{3}+\frac{1}{9}+\frac{1}{27}+\frac{1}{81}+\frac{1}{243}+\frac{1}{729}\)
c) \(\frac{1}{5}+\frac{1}{10}+\frac{1}{20}+\frac{1}{40}+...............+\frac{1}{1280}\) d) \(\frac{2}{3}+\frac{2}{6}+\frac{2}{12}+\frac{2}{24}+\frac{2}{48}+\frac{2}{96}+\frac{2}{192}\)
e) \(1+\frac{5}{4}+\frac{5}{8}+\frac{5}{16}+\frac{5}{32}+\frac{5}{64}\) f) \(\frac{3}{2}+\frac{3}{8}+\frac{3}{32}+\frac{3}{128}+\frac{3}{512}\)
g) \(3+\frac{3}{5}+\frac{3}{25}+\frac{3}{125}+\frac{3}{625}\)
Sao mà mình hỏi bài này từ lâu lắm rồi mà vẫn chưa có bạn nào trả lời nhỉ?
A) \(\dfrac{1}{2}+\dfrac{1}{4}+\dfrac{1}{8}+\dfrac{1}{16}+\dfrac{1}{32}+\dfrac{1}{64}\)
2A= \(1+\dfrac{1}{2}+\dfrac{1}{4}+\dfrac{1}{8}+\dfrac{1}{16}+\dfrac{1}{32}\)
2A-A = \(1-\dfrac{1}{32}\)
A= \(\dfrac{31}{32}\)
b)\(\dfrac{1}{3}+\dfrac{1}{9}+\dfrac{1}{27}+\dfrac{1}{81}+\dfrac{1}{243}+\dfrac{1}{729}\)
Dặt A=
3A= \(1+\dfrac{1}{3}+\dfrac{1}{9}+\dfrac{1}{27}+\dfrac{1}{81}+\dfrac{1}{243}\)
3A-A=\(1-\dfrac{1}{792}\)
2A= \(\dfrac{791}{792}\)
A= \(\dfrac{791}{792}:2=\dfrac{791}{1584}\)
Tính nhanh
a) 1/2 + 1/4 + 1/8 + 1/16 + 1/32 + 1/64 + 1/128 + 1/256
b) 1/3 + 1/9 + 1/27 + 1/81 + 1/243 + 1/729
a) A= 1/2 + 1/4+ 1/8+ 1/16 + 1/32 + 1/64 + 1/128 + 1/256 + 1/512
A = 1 - 1/2 + 1/2- 1/4 + 1/4 - 1/8 + 1/8 - 1/16 + 1/16 - 1/32 + 1/32 - 1/64 + 1/64 - 1/128 + 1/128 - 1/256 - 1/256 - 1/512
A = 1 - 1/512
A = 511/512
b) B = 1/3 + 1/9 + 1/27 + 1/81 + 1/243 + 1/729
3B = 1 + 1/3 + 1/9 + 1/27 + 1/81 + 1/243
3B - B = 1 - 1/729
2B = 728/729
B = 364/729
a) A= 1/2 + 1/4+ 1/8+ 1/16 + 1/32 + 1/64 + 1/128 + 1/256 + 1/512
A = 1 - 1/2 + 1/2- 1/4 + 1/4 - 1/8 + 1/8 - 1/16 + 1/16 - 1/32 + 1/32 - 1/64 + 1/64 - 1/128 + 1/128 - 1/256 - 1/256 - 1/512
A = 1 - 1/512
A = 511/512
b) B = 1/3 + 1/9 + 1/27 + 1/81 + 1/243 + 1/729
3B = 1 + 1/3 + 1/9 + 1/27 + 1/81 + 1/243
3B - B = 1 - 1/729
2B = 728/729
B = 364/729
gọi A là biểu thức trên
ta có : A = 1/2 + 1/4 + 1/8 + 1/16 + 1/32 + 1/64 + 1/128 + 1/256
2A = 2. ( 1/2 + 1/4 + ... + 1/256 )
2A = 1 + 1/2 + 1/4 + 1/8 + 1/16 +1/32 + 1/64 + 1/128
2A - A = ( 1 + 1/2 + 1/4 + 1/8 + 1/16 +1/32 + 1/64 + 1/128) - ( 1/2 + 1/4 + 1/8 + 1/16 + 1/32 + 1/64 + 1/128 + 1/256 )
A = 1 - 1/256
A = 255/256
tính nhanh:
a, 5/2 + 5/6 + 5/18 + 5/54+5/162+5/486
b, 2/3+2/6+2/12+2/24+2/48+2/96+2/192
c, 1/3+1/9+1/27+1/81+1/243+1/729
d, 3/2+3/8+3/32+3/128+3/512
e, 1/2.3+1/3.4+1/5.6+1/6.7+1/7.8
g, 4/3.7+4/7.11+4/11.15+4/15.19+4/19.23+4/23.27
h, 2/2.5+2/5.8+2/8.11+2/11.14+2/14.17
i, 4/1.3.5+4/3.5.7+4/5.7.9+4/7.9.11+4/9.11.13+4/11.13.15
k,2/1.2.3+2/2.3.4+2/3.4.5+2/4.5.6+2/5.6.7+2/6.7.8
2) . Viết thành dạng lũy thừa vơi số mũ lớn hơn 1 các số sau đây 1).8. 2).25 3).4 4).49 5).81 6).36 7).100 8).121 9).144 10).169 11).27 12).125 13).1000 14).32 15).243 16).343 17).216 18).64 19).225 20).128
1: 8=2^3
2: 25=5^2
3: 4=2^2
4: 49=7^2
5: 81=9^2
6: 36=6^2
7: 100=10^2
8: 121=11^2
9: 144=12^2
10: 169=13^2
11: 27=3^3
12: 125=5^3
13: 1000=10^3
14: 32=2^5
15: 243=3^5
16: 343=7^3
17: 216=6^3
18: 64=4^3
19: 225=15^2
20: 128=2^7
Bài 1: Tính nhanh
a) 1/2 + 1/4 + 1/8 + 1/16 + 1/32 + 1/128 + 1/256
b) 1/3 + 1/9 + 1/27 + 1/81 + 1/243 + 1/729
c)1/2 + 1/6 + 1/12 + 1/20 + 1/30
tính bằng 2 cách
nhanh nhé
bài 1 tính nhanh
mik xin sửa đề câu a thành thế này ~
\(a,\frac{1}{2}+\frac{1}{4}+\frac{1}{8}+\frac{1}{16}+\frac{1}{32}+\frac{1}{64}+\frac{1}{128}+\frac{1}{256}\)
đặt \(A=\frac{1}{2}+\frac{1}{4}+\frac{1}{8}+\frac{1}{16}+\frac{1}{32}+\frac{1}{64}+\frac{1}{128}+\frac{1}{256}\)
\(A\cdot2=1+\frac{1}{2}+\frac{1}{4}+\frac{1}{8}+\frac{1}{16}+\frac{1}{32}+\frac{1}{64}+\frac{1}{128}\)
\(A\cdot2-A=\) ( \(1+\frac{1}{2}+\frac{1}{4}+\frac{1}{8}+\frac{1}{16}+\frac{1}{32}+\frac{1}{64}+\frac{1}{128}\) ) - ( \(\frac{1}{2}+\frac{1}{4}+\frac{1}{8}+\frac{1}{16}+\frac{1}{32}+\frac{1}{64}+\frac{1}{128}+\frac{1}{256}\) )
\(A=1-\frac{1}{256}\)
\(A=\frac{255}{256}\)
\(b,\frac{1}{3}+\frac{1}{9}+\frac{1}{27}+\frac{1}{81}+\frac{1}{243}+\frac{1}{729}\)
đặt \(B=\) \(\frac{1}{3}+\frac{1}{9}+\frac{1}{27}+\frac{1}{81}+\frac{1}{243}+\frac{1}{729}\)
\(B\cdot3=1+\frac{1}{3}+\frac{1}{9}+\frac{1}{27}+\frac{1}{81}+\frac{1}{243}\)
\(B\cdot3-B=\) ( \(1+\frac{1}{3}+\frac{1}{9}+\frac{1}{27}+\frac{1}{81}+\frac{1}{243}\)) - \(\frac{1}{3}+\frac{1}{9}+\frac{1}{27}+\frac{1}{81}+\frac{1}{243}+\frac{1}{729}\) )
\(B\cdot2=\) \(1-\frac{1}{729}\)
\(B\cdot2=\frac{728}{729}\)
\(B=\frac{728}{729}:2\)
\(B=\frac{364}{729}\)
\(c,\frac{1}{2}+\frac{1}{6}+\frac{1}{12}+\frac{1}{20}+\frac{1}{30}\)
ĐẶT \(C=\frac{1}{2}+\frac{1}{6}+\frac{1}{12}+\frac{1}{20}+\frac{1}{30}\)
\(C=\frac{1}{1\cdot2}+\frac{1}{2\cdot3}+\frac{1}{3\cdot4}+\frac{1}{4\cdot5}+\frac{1}{5\cdot6}\)
\(C=\frac{1}{1}-\frac{1}{2}+\frac{1}{2}-\frac{1}{3}+\frac{1}{3}-\frac{1}{4}+\frac{1}{4}-\frac{1}{5}+\frac{1}{5}-\frac{1}{6}\)
\(C=\frac{1}{1}-\frac{1}{6}\)
\(C=\frac{5}{6}\)
1, a,81 mũ 2 :27 mũ 5 b, 6 mũ 4 . 32 mũ 3 c, 25 mũ 5 .125 mũ 3 2, 4 mũ n-1=64 5 mũ n+2=625 78<3 mũ n=1<813 16<2 mũ n-2<128 giúp với ạ còn tiếng nx làm nộp r
a
\(^{81^2=\left(3^4\right)^2}\)=\(3^8\)
..........(cần cù thì bù siêng năng chỉ có làm thì mới có ăn, mấy cái loại ko làm mà đòi có ăn thì ăn ĐẦU B**I)
1.Tính bằng 2 cách:
a) 3/4-1/6+5/8
b) 5/12+7/18-3/20
2.Tính :
13= 1/3+1/9+1/27+1/81+1/243
3. Tính tổng :
A=1/2+1/4+1/8+1/16+1/32+1/64
ai nhanh mình tick nha