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a. 2006/2005 x 2007/2006 x 2008/2007 x 2009/2008 x 2010/2009'
= 2006 x 2007 x 2008 x 2009 x 2010 / 2005 x 2006 x 2007 x 2008 x 2009
= 2010/2005
= 402/401
\(\left(1+\frac{1}{2005}\right)x\left(1+\frac{1}{2006}\right)x\left(1+\frac{1}{2007}\right)x\left(1+\frac{1}{2008}\right)x\left(1+\frac{1}{2009}\right)\)
\(=\frac{2006}{2005}x\frac{2007}{2006}x\frac{2008}{2007}x\frac{2009}{2008}x\frac{2010}{2009}\)
\(=\frac{2010}{2005}\)
\(=\frac{402}{401}\)
`a)4/5+5 1/2 xx (4,5-2)+7/10`
`=4/5+11/2*2,5+7/10`
`=0,8+2,2+0,7`
`=3+0,7=3,7`
`b)125%xx 17/4:(1 5/16-0,5)+2008`
`=1,25xx4,25:13/16+2008`
`=85/13+2008`
`=2014 7/13`
`c)5/11+(16/11+1)`
`=5/11+1+5/11+1`
`=2+10/11=32/11`
`d)3/17+11/4+5/8+14/17+3/8`
`=3/17+14/17+5/8+3/8+11/4`
`=1+1+11/4`
`=19/4`
a)
\(\dfrac{4}{5}+5\dfrac{1}{2}x\left(4,5-2\right)=\dfrac{7}{10}\)
<=> \(\dfrac{11}{2}x\times2,5=\dfrac{7}{10}-\dfrac{4}{5}=\dfrac{-1}{10}\)
<=> \(\dfrac{55}{4}x=\dfrac{-1}{10}< =>x=\dfrac{-2}{275}\)
b) \(125\%\times\dfrac{17}{4}:\left(1\dfrac{5}{16}-0,5\right)+2008\)
= \(\dfrac{85}{16}:\left(\dfrac{21}{16}-\dfrac{1}{2}\right)+2008=\dfrac{85}{16}:\dfrac{13}{16}+2008=\dfrac{26189}{13}\)
c) \(\dfrac{5}{11}+\left(\dfrac{16}{11}+1\right)\)
= \(\dfrac{21}{11}+1=\dfrac{32}{11}\)
d) \(\left(\dfrac{3}{17}+\dfrac{14}{17}\right)+\left(\dfrac{5}{8}+\dfrac{3}{8}\right)+\dfrac{11}{4}\)
= 1 + 1 + \(\dfrac{11}{4}\) = \(\dfrac{19}{4}\)
\(2009-\left(4\frac{5}{9}+x-7\frac{7}{8}\right):15\frac{3}{2}=2008\)
\(\Leftrightarrow2009-\left(\frac{41}{9}+x-\frac{63}{8}\right):\frac{33}{2}=2008\)
\(\Leftrightarrow2009-\left(x-\frac{239}{72}\right):\frac{33}{2}=2008\)
\(\Leftrightarrow2009-\frac{2x}{33}+\frac{239}{1188}=2008\)
\(\Leftrightarrow\frac{-2x}{33}=\frac{-1427}{1188}\)
\(\Leftrightarrow-2376x=-47091\)
\(\Leftrightarrow x=\frac{1427}{72}\)
\(A=\frac{2007\cdot\left(2008-1008\right)}{\left(2007-1007\right)+\left(2008-1008\right)}=\frac{2007\cdot1000}{1000+1000}=\frac{2007}{2}\)
\(B=\frac{1978\cdot1979+\left(1979+1\right)\cdot21+\left(1979-21\right)}{1979\cdot\left(1980-1978\right)}=\frac{1979\cdot\left(1978+21\right)}{1979\cdot2}=\frac{1999}{2}\)
\(\frac{1}{8}=12,5\%\) ; \(\frac{1}{16}=6,25\%\) ; \(\frac{1}{2}=50\%\) ; \(\frac{1}{4}=25\%\)
Thay vào trên mà tính.
= \(1+\left(\frac{3\left(1x2+2x4x2\right)}{3\left(5+5x3x25\right)}+1\right)-\left(1+\frac{18}{54}\right)-1\) = \(\frac{18}{380}-\frac{18}{54}\)
Mình không tin đây là toán lớp 5 đâu ! ( TẠI VÌ MÌNH CHƯA HỌC ) ^_^
( x . 25 + 2008 ) . 2009 = ( 575 + 2008 ) . 2009
=> x . 25 + 2008 = 575 + 2008
=> x . 25 = 575
x = 575 : 25
x = 23
Dấu " . " là dấu nhân nha
=>x . 25 +2008 =575+2008
=>x.25=575
x=575:5
x=115