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a; A = \(\dfrac{4026\times2014+4030}{2013\times2016-2011}\)
A = \(\dfrac{2\times\left(2013\times2014+2015\right)}{2013\times2016-2011}\)
A = \(\dfrac{2\times\left(2013\times2016-2013\times2+2015\right)}{2013\times2016-2011}\)
A = \(\dfrac{2\times\left(2013\times2016-4026+2015\right)}{2013\times2016-2011}\)
A = \(\dfrac{2\times\left(2013\times2016-2011\right)}{2013\times2016-2011}\)
A = 2
a) \(\dfrac{2}{3}+\dfrac{3}{5}=\dfrac{10}{15}+\dfrac{9}{15}=\dfrac{19}{15}\)
a) \(\dfrac{7}{12}-\dfrac{2}{7}+\dfrac{1}{12}=\dfrac{2}{3}-\dfrac{2}{7}=\dfrac{14}{21}-\dfrac{6}{21}=\dfrac{8}{21}\)
a; (5142 - 17 x 8 + 242 : 11) x (27 - 3 x 9)
= (5142 - 17 x 8 + 242 : 11) x (27 - 27)
= (5142 - 17 x 8 + 242 : 11) x 0
= 0
b;
(1 + \(\dfrac{1}{2}\)) \(\times\) (1 + \(\dfrac{1}{3}\)) \(\times\) ( 1 + \(\dfrac{1}{4}\)) \(\times\) ... \(\times\) (1 + \(\dfrac{1}{2010}\)) \(\times\)(1 + \(\dfrac{1}{2011}\))
= \(\dfrac{2+1}{2}\) \(\times\) \(\dfrac{3+1}{3}\) \(\times\) \(\dfrac{4+1}{4}\)\(\times\) ... \(\times\) \(\dfrac{2010+1}{2010}\)\(\times\) \(\dfrac{2011+1}{2011}\)
= \(\dfrac{3}{2}\)\(\times\)\(\dfrac{4}{3}\)\(\times\)\(\dfrac{5}{4}\)\(\times\)...\(\times\)\(\dfrac{2011}{2010}\)\(\times\)\(\dfrac{2012}{2011}\)
= \(\dfrac{2012}{2}\)
= 1006
=13/12x14/13x15/14x16/15x...x2006/2005x2007/2006x2008/2007
=2008/12
=502/3
A = 1\(\dfrac{1}{12}\) \(\times\) 1\(\dfrac{1}{13}\) \(\times\) 1\(\dfrac{1}{14}\) \(\times\) 1\(\dfrac{1}{15}\) \(\times\) ... \(\times\) 1\(\dfrac{1}{2005}\) \(\times\) 1\(\dfrac{1}{2006}\) \(\times\) 1\(\dfrac{1}{2007}\)
A = ( 1 + \(\dfrac{1}{12}\)) \(\times\) ( 1 + \(\dfrac{1}{13}\)) \(\times\) ( 1 + \(\dfrac{1}{14}\)) \(\times\)...\(\times\) ( 1 + \(\dfrac{1}{2006}\))\(\times\)(1+\(\dfrac{1}{2007}\))
A = \(\dfrac{13}{12}\) \(\times\) \(\dfrac{14}{13}\) \(\times\) \(\dfrac{15}{14}\) \(\times\) ...\(\times\) \(\dfrac{2007}{2006}\) \(\times\) \(\dfrac{2008}{2007}\)
A = \(\dfrac{13\times14\times15\times...\times2007}{13\times14\times15\times...\times2007}\) \(\times\) \(\dfrac{2008}{12}\)
A = 1 \(\times\) \(\dfrac{502}{3}\)
A = \(\dfrac{502}{3}\)
Ta có công thức tổng quát:
\(\dfrac{k}{n\cdot\left(n+k\right)}=\dfrac{1}{n}-\dfrac{1}{n+k}\)
\(a,A=\dfrac{1}{5\cdot8}+\dfrac{1}{8\cdot11}+...+\dfrac{1}{x\left(x+3\right)}\\ =\dfrac{1}{3}\left(\dfrac{3}{5\cdot8}+\dfrac{3}{8\cdot11}+...+\dfrac{3}{x\left(x+3\right)}\right)\\ =\dfrac{1}{3}\left(\dfrac{1}{5}-\dfrac{1}{8}+\dfrac{1}{8}-\dfrac{1}{11}+...+\dfrac{1}{x}-\dfrac{1}{x+3}\right)\\ =\dfrac{1}{3}\cdot\left(\dfrac{1}{5}-\dfrac{1}{x+3}\right)\\ =\dfrac{1}{3}\cdot\dfrac{x-2}{5\left(x+3\right)}\\ =\dfrac{x-2}{15\left(x+3\right)}\)
Theo đề bài ta có:
\(A=\dfrac{101}{1540}\\ \Rightarrow\dfrac{x-2}{15\left(x+3\right)}=\dfrac{101}{1540}\\ \Rightarrow\dfrac{x-2}{x+3}=\dfrac{303}{308}\\ \Rightarrow\dfrac{x-2}{x+3}=\dfrac{305-2}{305+3}\\ \Rightarrow x=305\)
a,(11/15+4/15)+(5/7+2/7)
=1+1
=2
b,5/9x(1/2+6/4)
=5/9x2
=10/9
c,1/2:(7/8+9/8)
=1/2:2
=1
d,(17/10-7/10)+1/2
=1+1/2
=3/2
`a) 19/7 + 5/6 = 114/42 + 35/42 = 149/42`
`b) 17/6 - 2 = 17/6 - 12/6 = 5/6`
`c) 9 x 7/10 = 63/10`
`d) 11/7 : 22/21 = 11/7 . 21/22 = 3/2`
a=149/42,b=5/6,c63/10,d=3/2
a)19/7+5/6=114/42+35/42=149/42
b) 17/6-2= 17/6 -12/6=5/6
a) \(\frac{19}{7} + \frac{5}{6} = \frac{114}{42} + \frac{35}{42} = \frac{149}{42}\)
b) \(\frac{17}{6} - 2 = \frac{17}{6} - \frac{12}{6} = \frac{5}{6}\)
c) \(9 \times \frac{7}{10} = \frac{9 \times 7}{10} = \frac{63}{10}\)
d) \(\frac{11}{7} : \frac{22}{21} = \frac{11}{7} \times \frac{21}{22} = \frac{3}{2}\)
l
19/7 + 5/6= 114/42 + 25/42 = 149/42
17/6 + 2= 17/6 + 12/6 = 29/6
9 * 7/10 =63/10
11/7 : 22/21 = 11/7 * 21/22 = 231/154
Không có đáp án
Sao làm được
a)149/42
b)5/6
c)63/10
d)3/2
\(\frac{63}{80}\) \(\frac{15}{6}\)
\(\frac{24}{42}\)
19/7+5/6=114/42+30/42=144
17/6-2=17/6-12/6=5
9×7/10=63/90
11/7÷22/21/=231/147÷154/147=15/147
A : 159 phần 42
B : 5 phần 6
C : 63 phần 10
D : 3 phần 2
Ummmmmmmmmmmm🤫🤫🤫🤫🤫🤫😈😈😈😈😈😈😈😈😈
19/7+5/6 = 144/42
17/6 - 2 = 11/12
9 * 7/10= 63/10
11/7 : 22/21= 231/154
A' 114 phần 42 + 35/42 = 114 + 35/42 = 149/42
B17/6 - 12/6 = 17 - 12/6 = 5/6
C 9 x 7/10 = 9/1 x 7/10 = 9 x 7/1 x 10 = 63/10
D' 11/7 x 21/22 = 1 x 3/1 x 2 = 3/2
\(\frac{149}{42}\)
\(\frac56\)
\(\frac{63}{10}\)
\(\frac{231}{154}\)
A= 547619
G
19/7 +5/6 = 19/7 + 5 = 24/7
17/6 - 2 = 17/6 - 2 = 15/6
9 ×7/10 = 9 × 7/10 = 63/10
11/7 ÷ 22/21 = 11 × 21 = 231/154
7× 22
A 24/13, b 15/6, c 63/90, d 231/154
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149.
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42.