A=5/9+2/15-6/9
B=2/7-3/8+4/7+1/7-5/8+5/15
C=3/5+1/15+1/57+1/3-2/9-3/4-1/36
D=1/1x2+1/2x3+1/3x4+...+1/99x100
E=1-3/1x3-3/3x5-3/5x7-...-19
help plssssssss
[ 1/3 + 1/5 ] + [ 1/6 - 1/5 ]
3/16 x 7/5 + 3/5 x 9/16
1/1x2 + 1/2x3 + 1/ 3x4 + ...... + 1/2020x2021
1/1x3 + 1/3x5 + 1/5x7 + ..... + 1/2021 x 2023
3/2 x 1/7 x 5/4 + 15/2 x 6/7 x 1/4
NHỜCÁC BN LM GIÚP MIK GẤP CHIỀU NAY MIK CẦN ÒI !!!!!~~~
TÍNH BẰNG CÁCH NHANH NHẤT NHA CÁC BN
a) \(\left(\frac{1}{3}+\frac{1}{5}\right)+\left(\frac{1}{6}-\frac{1}{5}\right)=\left(\frac{1}{3}+\frac{1}{6}\right)+\left(\frac{1}{5}-\frac{1}{5}\right)=\frac{1}{2}\)
b) \(\frac{3}{16}\times\frac{7}{5}+\frac{3}{5}\times\frac{9}{16}=\frac{21}{80}+\frac{27}{80}=\frac{48}{80}=\frac{3}{5}\)
c) \(\frac{1}{1\times2}+\frac{1}{2\times3}+...+\frac{1}{2020\times2021}=1-\frac{1}{2}+\frac{1}{2}-\frac{1}{3}+...+\frac{1}{2020}-\frac{1}{2021}\)
\(=1-\frac{1}{2021}=\frac{2020}{2021}\)
d) \(\frac{1}{1\times3}+\frac{1}{3\times5}+...+\frac{1}{2021\times2023}=\frac{1}{2}\times\left(\frac{2}{1\times3}+\frac{2}{3\times5}+...+\frac{2}{2021\times2023}\right)\)
\(=\frac{1}{2}\times\left(1-\frac{1}{3}+\frac{1}{3}-\frac{1}{5}+...+\frac{1}{2021}-\frac{1}{2023}\right)\)
\(=\frac{1}{2}\times\left(1-\frac{1}{2023}\right)=\frac{1}{2}\times\frac{2022}{2023}=\frac{1011}{2023}\)
e) \(\frac{3}{2}\times\frac{1}{7}\times\frac{5}{4}+\frac{15}{2}\times\frac{6}{7}\times\frac{1}{4}==\frac{15}{56}+\frac{80}{56}=\frac{95}{56}\)
Tính hợp lí nếu có thể:
a)3/7+4/9+4/7+5/9
b)1/5+4/10+9/15+16/20+25/25+36/30+49/35+64/40+81/45
c)1/8+1/12+3/8+5/12
d)(1-1/2)x(1-1/3)x(1-1/4)x...x(1-100)
e)9/5:17/15+8/5:17/15
f)2/1x2+2/2x3+2/3x4+...+2/19x20
Ai nhanh nhất mình tick cho
a) 3/7 + 4/9 + 4/7 + 5/9
= ( 3/7 + 4/7 ) + ( 4/9 + 5/9 )
= 7/7 + 9/9
= 1 + 1
= 2
b)1/5 + 4/10 + 9/15 + 16/20 + 25/25 + 36/30 + 49/35 + 64/40 + 81/45
= 1/5 + 2/5 + 3/5 + 4/5 + 5/5 + 6/5 + 7/5 + 8/5 + 9/5
= ( 1/5 + 9/5 ) + ( 2/5 + 8/5 ) + (7/5 + 3/5 ) + ( 4/5 + 6/5 ) + 5/5
= 2 + 2 + 2 + 2 + 1
= 2 x 4 + 1
= 8 +1
= 9
c) 1/8 + 1/12 + 3/8 + 5/12
= ( 1/8 + 3/8 ) + ( 1/12 + 5/12)
= 4/8 + 6/12
= 1/2 + 1/2
= 2/4 = 1/2
mỏi tay rồi
Tính hợp lí ( Giúp mk với )
A = (-4/5 + 4/3) + (-5/4 + 14/5) - 7/3
B = 8/3 x 2/5 x 3/8 x 10 x 19/92
C = -5/7 x 2/11 + (-5)/7 x 9/14 + 1/57
D = 12/19 x 7/15 x (-13)/17 x 19/12 x 17/13
E = 1/1x2 + 1/2x3 + 1/3x4 + ....+ 1/49 x 50
A = ( -4/5 + 4/3 ) + (-5/4 + 14/5) - 7/3
= 8/15 + 31/20 - 7/3
= 25/12 - 7/3
= -1/4
B = 8/3 x 2/5 x 3/8 x 10x 19/92
= 16/15 x 15/4 x 19/92
= 4x19/92
= 19/23
Bài 1
a)5x7 phần 15 b)8:16 phần 23 c)8 phần 15 :5
d)15 phần 19 x3
Bài 2 :
3x4/9+2/3-7/18
7/10x2/3-1/4
9/8-7/8:5/6
2/3+1/2:3/2-11/24
Bài 3 Một hình bình hành có chiều cao 3/5m độ dài đáy gập 2 lần chiều cao,cạnh bên là 4/5m tính chu vi và diện tích của hình bình hành đó.
1. Tính
a) 5/7 x 4 : 5/9
b) 8 x 2/3 : 1/2
c) 6 : 3/5 - 7/6 x 6/7
21/5 x 10/11 + 57/11
2. Tìm x
a) 35/9 : x = 35/6
b) (1/1x2 + 1/2x3 + 1/3x4 +1/4x5 +1/5x6) x 10- x = 0
1> a) \(\frac{5}{7}x4:\frac{5}{9}=\frac{5}{7}:\frac{5}{9}x4=\frac{5}{7}x\frac{9}{5}x4=\frac{9}{7}x4=\frac{9x4}{7}=\frac{36}{7}\)
\(b,8x\frac{2}{3}:\frac{1}{2}=8x\frac{2}{3}x\frac{2}{1}=8x2x\frac{2}{3}=16x\frac{2}{3}=\frac{32}{3}\)
\(c,6:\frac{3}{5}-\frac{7}{6}x\frac{6}{7}=6x\frac{5}{3}-1=10-1=9\)
\(\frac{21}{5}x\frac{10}{11}+\frac{57}{11}=\frac{42}{11}+\frac{57}{11}=\frac{99}{11}=9\)
2) a) \(\frac{35}{9}:x=\frac{35}{6}\)
\(x=\frac{35}{9}:\frac{35}{6}\)
\(x=\frac{35}{9}x\frac{6}{35}\)
\(x=\frac{2}{3}\)
b) \(\left(\frac{1}{1x2}+\frac{1}{2x3}+\frac{1}{3x4}+\frac{1}{4x5}+\frac{1}{5x6}\right)x10-X=0\)
\(\left(\frac{1}{1}-\frac{1}{2}+\frac{1}{2}-\frac{1}{3}+.....+\frac{1}{5}-\frac{1}{6}\right)x10-X=0\)
\(\left(\frac{1}{1}-\frac{1}{6}\right)x10-X=10\)
\(\frac{5}{6}x10-X=0\)
\(X=\frac{5}{6}x10=\frac{25}{3}\)
Đúng nha !!!!
1/a/\(\frac{5}{7}\cdot4:\frac{5}{9}=\frac{20}{7}:\frac{5}{9}=\frac{20}{7}\cdot\frac{9}{5}=\frac{36}{7}\)
b/\(8\cdot\frac{2}{3}:\frac{1}{2}=\frac{16}{3}:\frac{1}{2}=\frac{16}{3}\cdot\frac{2}{1}=\frac{32}{3}\)
c/\(6:\frac{3}{5}-\frac{7}{6}\cdot\frac{6}{7}=6\cdot\frac{5}{3}-1=10-1=9\)
2/a/\(\frac{35}{9}:x=\frac{35}{6}\)
\(x=\frac{35}{9}:\frac{35}{6}=\frac{35}{9}\cdot\frac{6}{35}\)
\(x=\frac{2}{3}\)
b/\(\left(\frac{1}{1\cdot2}+\frac{1}{2\cdot3}+\frac{1}{3\cdot4}+\frac{1}{4\cdot5}+\frac{1}{5\cdot6}\right)\cdot10-x=0\)
\(\left(\frac{1}{2}+\frac{1}{6}+\frac{1}{12}+\frac{1}{20}+\frac{1}{30}\right)\cdot10-x=0\)
\(\left(\frac{30}{60}+\frac{10}{60}+\frac{5}{60}+\frac{2}{30}\right)\cdot10-x=0\)
\(\frac{47}{60}\cdot10-x=0\)
\(\frac{47}{6}-x=0\)
\(x=\frac{47}{6}-0\)
\(x=\frac{47}{6}\)
bai 1 tinh nhanh
a . 1/5x6 +1/6x7+ 1/7x8 + 1/8x9 +1/9x10
b . 1/1x2 + 1/2x3 + ....... + 1/99x100
c . 2/3x5 + 2/5x7 + 2/7x8 + 2/8x9
d . 2/3x5 + 2/5x7 + .......+ 2/98x100
bai 2 tinh hop li
9/13 + 14/6 + 1/9 + 4/6 + 7/13 + 17/19
bai 3 dien dau ( > , < , = )
a . 3/4 + 5/2 ....... 5/8 + 2 3/5 ( hon so )
B . 3 1/5 - 8/3 ......... 17/5 - 2 12/5 hon so
c . 2 4/9 + 18/7......... 22/9 + 2 4/7
giup mk nha cac ban , mai mk phai nop bai roi toi nay mk se lay y kien cua cac ban , giup mk nha
b1
a) \(\dfrac{1}{5.6}+\dfrac{1}{6.7}+\dfrac{1}{7.8}+\dfrac{1}{8.9}+\dfrac{1}{9.10}\)
\(=\dfrac{1}{5}-\dfrac{1}{6}+\dfrac{1}{6}-\dfrac{1}{7}+\dfrac{1}{7}-\dfrac{1}{8}+\dfrac{1}{8}-\dfrac{1}{9}+\dfrac{1}{9}-\dfrac{1}{10}\)
\(=\dfrac{1}{5}-\dfrac{1}{10}\)
\(=\dfrac{2}{10}-\dfrac{1}{10}\)
\(=\dfrac{1}{10}\)
b) \(\dfrac{1}{1.2}+\dfrac{1}{2.3}+...+\dfrac{1}{99.100}\)
\(=\dfrac{1}{1}-\dfrac{1}{2}+\dfrac{1}{2}-\dfrac{1}{3}+...+\dfrac{1}{99}-\dfrac{1}{100}\)
\(=\dfrac{1}{1}-\dfrac{1}{100}\)
\(=\dfrac{99}{100}\)
c) \(\dfrac{2}{3.5}+\dfrac{2}{5.7}+\dfrac{2}{7.9}+\dfrac{2}{9.11}\)
\(=\dfrac{1}{3}-\dfrac{1}{5}+\dfrac{1}{5}-\dfrac{1}{7}+\dfrac{1}{7}-\dfrac{1}{9}+\dfrac{1}{9}-\dfrac{1}{11}\)
\(=\dfrac{1}{3}-\dfrac{1}{11}\)
\(=\dfrac{8}{33}\)
d) \(\dfrac{2}{3.5}+\dfrac{2}{5.7}+...+\dfrac{2}{99.101}\)
\(=\dfrac{1}{3}-\dfrac{1}{5}+\dfrac{1}{5}-\dfrac{1}{7}+...+\dfrac{1}{99}-\dfrac{1}{101}\)
\(=\dfrac{1}{3}-\dfrac{1}{101}\)
\(=\dfrac{98}{303}\)
Tính:
2/7 + 5/7 8/15 + 6/15 2/9 + 3/9 + 4/9
[ Không cần làm phép tính ]Điền vào ô trống <,>,= :
3/5 + 1/5 ... 1/5 + 3/5
7/9 + 1/9 ... 7/9 + 1/9 + 1/9
3/7 + 2/7 ... 3/7 + 4/7
1/5 + 3/5 ... 2/5 + 3/5
Tính:
2/7 + 5/7=1
8/15 + 6/15 =14/15
2/9 + 3/9 + 4/9=9/9=1
[ Không cần làm phép tính ]Điền vào ô trống <,>,= :
3/5 + 1/5 = 1/5 + 3/5
7/9 + 1/9 < 7/9 + 1/9 + 1/9
3/7 + 2/7 < 3/7 + 4/7
1/5 + 3/5 < 2/5 + 3/5
Tính:
2/7 + 5/7=1
8/15 + 6/15 =14/15
2/9 + 3/9 + 4/9=9/9=1
[ Không cần làm phép tính ]Điền vào ô trống <,>,= :
3/5 + 1/5 = 1/5 + 3/5
7/9 + 1/9 < 7/9 + 1/9 + 1/9
3/7 + 2/7 < 3/7 + 4/7
1/5 + 3/5 < 2/5 + 3/5
a. 2+3/4 b.1/3+3/2-7/4 c.1/6+3/8-1/4 d.5/12+3/8x4/9 e.4/5-1/5x7/2 f.16/9-4/15:2/5
a) \(2+\dfrac{3}{4}\)
\(=\dfrac{8}{4}+\dfrac{3}{4}\)
\(=\dfrac{8+3}{4}\)
\(=\dfrac{11}{4}\)
b) \(\dfrac{1}{3}+\dfrac{3}{2}-\dfrac{7}{4}\)
\(=\dfrac{4}{12}+\dfrac{18}{12}-\dfrac{21}{12}\)
\(=\dfrac{4+18-21}{12}\)
\(=\dfrac{1}{12}\)
c) \(\dfrac{1}{6}+\dfrac{3}{8}-\dfrac{1}{4}\)
\(=\dfrac{4}{24}+\dfrac{9}{24}-\dfrac{6}{24}\)
\(=\dfrac{4+9-6}{24}\)
\(=\dfrac{7}{24}\)
d) \(\dfrac{5}{12}+\dfrac{3}{8}\times\dfrac{4}{9}\)
\(=\dfrac{5}{12}+\dfrac{3\times4}{8\times9}\)
\(=\dfrac{5}{12}+\dfrac{1}{6}\)
\(=\dfrac{5}{12}+\dfrac{2}{12}\)
\(=\dfrac{7}{12}\)
e) \(\dfrac{4}{5}-\dfrac{1}{5}\times\dfrac{7}{2}\)
\(=\dfrac{4}{5}-\dfrac{1\times7}{5\times2}\)
\(=\dfrac{4}{5}-\dfrac{7}{10}\)
\(=\dfrac{8}{10}-\dfrac{7}{10}\)
\(=\dfrac{8-7}{10}\)
\(=\dfrac{1}{10}\)
f) \(\dfrac{16}{9}-\dfrac{4}{15}:\dfrac{2}{5}\)
\(=\dfrac{16}{9}-\dfrac{4}{15}\times\dfrac{5}{2}\)
\(=\dfrac{16}{9}-\dfrac{4\times5}{15\times2}\)
\(=\dfrac{16}{9}-\dfrac{2}{3}\)
\(=\dfrac{16}{9}-\dfrac{6}{9}\)
\(=\dfrac{16-6}{9}\)
\(=\dfrac{10}{9}\)
a: =8/4+3/4=11/4
b: =4/12+18/12-21/12=1/12
c: =4/24+9/24-6/24=7/24
d: =5/12+12/72
=5/12+1/6
=5/12+2/12=7/12
e: =4/5-7/10
=8/10-7/10=1/10
f: =16/9-4/15*5/2
=16/9-20/30
=16/9-2/3
=16/9-6/9=10/9
`@` `\text {Ans}`
`\downarrow`
`a,`
`2 + 3/4`
`= 8/4 + 3/4`
`= 11/4`
`b,`
`1/3 + 3/2 - 7/4`
`= 4/12 + 18/12 - 21/12`
`= 1/12`
`c,`
`1/6 + 3/8 - 1/4`
`= 4/24 + 9/24 - 6/24`
`=7/24`
`d,`
`5/12+3/8 \times 4/9`
`= 5/12 + 27/32`
`= 121/96`
`e,`
`4/5-1/5 \times 7/2`
`= 4/5 - 2/35`
`=26/35`
`f,`
`16/9-4/15 \div 2/5`
`= 16/9 - 2/3`
`= 10/9`
$#KDN040510$
a) 1+4/3
b) 5/9 : 2/3
c ) 4/3-1/3x5/2
d) ( 3/2-3/8):1/2
e) 15/16 : 3/8 x 3/4
f) 7/19 x 1/3 x 7/19 x 2/3
g) 3/5x 8/27 x 25/3
h) 1/5 + 4/11 + 4/5 + 7/11
a)\(=\dfrac{3}{3}+\dfrac{4}{3}=\dfrac{7}{3}\)
b)\(=\dfrac{5}{9}\times\dfrac{3}{2}=\dfrac{15}{18}=\dfrac{5}{6}\)
d)\(=\left(\dfrac{12}{8}-\dfrac{3}{8}\right)\times2=\dfrac{9}{8}\times2=\dfrac{18}{8}=\dfrac{9}{4}\)
c)\(=\dfrac{4}{3}-\dfrac{5}{6}=\dfrac{8}{6}-\dfrac{5}{6}=\dfrac{3}{6}=\dfrac{1}{2}\)
a) 1 + 4/3 = 7/3
b) 5/9 : 2/3 = 5/6
c ) 4/3 -1/3 x 5/2
= 1 x 5/2
= 5/2
d) ( 3/2 - 3/8) : 1/2
= 9/8 : 1/2
= 9/4
e) 15/16 : 3/8 x 3/4
= 5/2 x 3/4
= 15/8
f) 7/19 x 1/3 x 7/19 x 2/3
= 7/19 x (1/3 x 2/3)
= 7/19 x 2/9
= 14/171
g) 3/5 x 8/27 x 25/3
= 3/5 x 25/3 x 8/27
= 5 x 8/27
= 40/27
h) 1/5 + 4/11 + 4/5 + 7/11
= (1/5 + 4/5) + (4/11 + 7/11)
= 1 + 1
= 2
e)\(\dfrac{15}{16}\times\dfrac{8}{3}\times\dfrac{3}{4}=\dfrac{360}{192}=\dfrac{15}{8}\)
f) \(=\dfrac{7}{19}\times\left(\dfrac{1}{3}+\dfrac{2}{3}\right)=\dfrac{7}{19}\times\dfrac{3}{3}=\dfrac{7}{19}\)
g)\(=\dfrac{600}{120}=\dfrac{600:120}{120:120}=\dfrac{5}{1}=5\)
h)\(=\left(\dfrac{1}{5}+\dfrac{4}{5}\right)+\left(\dfrac{4}{11}+\dfrac{7}{11}\right)=\dfrac{5}{5}+\dfrac{11}{11}=1+1=2\)