Tính nhanh mk tick:
2005 x 2008 x 5 x 6 x11 x13 x 1978 x 1979 x 24 x 8 x 26 x 11 = ???
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cọc a ko bik làm :)))
b) 1980 x 1979 - 1978 x 1979
= ( 1980 - 1978 ) x 1979
= 2 x 1979
= 3958
Chúc bạn hok tốt!~~~
b) 1980 . 1979 - 1978 . 1979
= 1979 ( 1980 - 1978 )
=1979 . 2
= 3958
=))
b. \(\dfrac{4.2.3.5.2.6.2.5.3}{4.3.4.5.6.4.5.6}=\dfrac{1}{4}\)
c. \(\dfrac{17.2.101.2005}{17.2.101.2.2005}=\dfrac{1}{2}\)
d. \(\dfrac{2.3.4.2.11.13.17}{3.11.4.4.17.13.2}=\dfrac{1}{2}\)
a)\(\dfrac{4\times6\times10\times12\times15}{4\times12\times5\times24\times30}=\dfrac{2}{2\times2\times2}=\dfrac{2}{8}=\dfrac{1}{4}\)
b)\(\dfrac{34\times101\times2005}{17\times202\times4010}=\dfrac{2}{2\times2}=\dfrac{2}{4}=\dfrac{1}{2}\)
c)\(\dfrac{6\times8\times11\times13\times17}{33\times16\times17\times26}=\dfrac{6}{3\times2\times2}=\dfrac{1}{2}\)
1979 x 1979 + 1980 x 1958 / 1980 x 1979 - 1978 x 1979
= (1979x1979-1978x1979) + \(\frac{1980X1958}{1980X1979}\)
= (1979-1978) x 1979 + \(\frac{1958}{1979}\)
= 1 x 1979 x \(\frac{1958}{1979}\)
= 1979 x \(\frac{1958}{1979}\)
=\(\frac{1979X1958}{1979}\)
=\(1958\)
GHI RÕ TỪNG CHI TIẾT , CHÚC BẠN HỌC TỐT !!!!!
Ta có: \(26\times8+4\times13-10\times26\)
\(=13\times2\times8+4\times13-10\times2\times13\)
\(=13\times16+4\times13-20\times13\)
\(=13\times\left(16+4-20\right)=13\times0=0\)
1) \(A=\frac{7}{10\times11}+\frac{7}{11\times12}+\frac{7}{12\times13}+...+\frac{7}{69\times70}\)
\(A=7\times\left(\frac{1}{10\times11}+\frac{1}{11\times12}+\frac{1}{12\times13}+...+\frac{1}{69\times70}\right)\)
\(A=7\times\left(\frac{1}{10}-\frac{1}{11}+\frac{1}{11}-\frac{1}{12}+\frac{1}{12}-\frac{1}{13}+...+\frac{1}{69}-\frac{1}{70}\right)\)
\(A=7\times\left(\frac{1}{10}-\frac{1}{70}\right)\)
\(A=7\times\frac{3}{35}\)
\(A=\frac{3}{5}\)
2) \(B=\frac{1}{25\times27}+\frac{1}{27\times29}+\frac{1}{29\times31}+...+\frac{1}{73\times75}\)
\(B=\frac{1}{2}\times\left(\frac{2}{25\times27}+\frac{2}{27\times29}+\frac{2}{29\times31}+...+\frac{2}{73\times75}\right)\).
\(B=\frac{1}{2}\times\left(\frac{1}{25}-\frac{1}{27}+\frac{1}{27}-\frac{1}{29}+\frac{1}{29}-\frac{1}{31}+...+\frac{1}{73}-\frac{1}{75}\right)\)
\(B=\frac{1}{2}\times\left(\frac{1}{25}-\frac{1}{75}\right)\)
\(B=\frac{1}{2}\times\frac{2}{75}\)
\(B=\frac{1}{75}\)
3) \(C=\frac{4}{2\times4}+\frac{4}{4\times6}+\frac{4}{6\times8}+...+\frac{4}{2008\times2010}\)
\(C=\frac{4}{2}\times\left(\frac{2}{2\times4}+\frac{2}{4\times6}+\frac{2}{6\times8}+...+\frac{2}{2008\times2010}\right)\)
\(C=2\times\left(\frac{1}{2}-\frac{1}{4}+\frac{1}{4}-\frac{1}{6}+\frac{1}{6}-\frac{1}{8}+...+\frac{1}{2008}-\frac{1}{2010}\right)\)
\(C=2\times\left(\frac{1}{2}-\frac{1}{2010}\right)\)
\(C=2\times\frac{502}{1005}\)
\(C=\frac{1004}{1005}\)
_Chúc bạn học tốt_
2010 x 2010 - 2009 x 2011
= ( 2011 - 2010 ) x 2010 - 2009 x 2011
= 2011 x 2010 - 1 x 2010 - 2009 x 2011
= 2011 x ( 2010 - 2009 ) - 1 x 2010
= 2011 x 1 - 2010
= 2011 - 2010
= 1
( 456 x 11 + 912 ) x 37 : ( 13 x 74 )
= ( 456 x 11 + 456 x 2 ) x 37 : ( 13 x 74 )
= [ 456 x ( 11 + 2 ) ] x 37 : ( 13 x 74 )
= [ 456 x 13 ] x 37 : ( 13 x 74 )
= 13 x 456 x 37 : ( 13 x 37 x 2 )
= 13 x 37 x 2 x 228 : ( 13 x 37 x 2 )
= ( 13 x 37 x 2 ) x 228 : ( 13 x 37 x 2 )
= ( 13 x 37 x 2 ) : ( 13 x 37 x 2 ) x 228
= 1 x 228
= 228
(44 x 52 x 60) : (11 x13 x 15 )
= [ ( 4 x 11 ) x ( 4 x 13 ) x ( 4 x 15 ) ] : (11 x13 x 15 )
= [ 4 x 11 x 4 x 13 x 4 x 15 ] : (11 x13 x 15 )
= [ ( 4 x 4 x 4 ) x ( 11 x 13 x 15 ) ] : (11 x13 x 15 )
= 64 x (11 x13 x 15 ) : (11 x13 x 15 )
= 64 x 1
= 64
a) 2010 x 2010 - 2009 x 2011
= 2010 x 2010 - [ 2009 x ( 2010 +1) ]
=2010 x 2010 - 2009 x 2010 - 2009
=2010( 2010 - 2009 ) -2009
= 2010 -2019
= 1
c) ( 44 x 52 x60 ) : (11x13x15)
\(\frac{44\cdot52\cdot60}{11\cdot13\cdot15}=\frac{4\cdot11\cdot4\cdot13\cdot4\cdot15}{11\cdot13\cdot15}=64\)
B) (456 x 11 +912) x 37 : ( 13 x 74 )
= \(\frac{\left(456\cdot11+912\right)\cdot37}{13\cdot74}=\frac{\left[456\left(11+2\right)\right]\cdot37}{13\cdot37}=\frac{456\cdot13}{13\cdot2}=\frac{456}{2}=228\)
Nhớ k mik nha bn
Ta có : \(\dfrac{x-2012}{8}+\dfrac{x-2008}{6}+\dfrac{x-2005}{5}=10-\dfrac{x-2004}{4}\)
\(\Leftrightarrow\left(\dfrac{x-2012}{8}-1\right)+\left(\dfrac{x-2008}{6}-2\right)+\left(\dfrac{x-2005}{5}-3\right)+\left(\dfrac{x-2004}{4}-4\right)=0\)\(\Leftrightarrow\dfrac{x-2020}{8}+\dfrac{x-2020}{6}+\dfrac{x-2020}{5}+\dfrac{x-2020}{4}=0\)
\(\Leftrightarrow\left(x-2020\right).\left(\dfrac{1}{8}+\dfrac{1}{6}+\dfrac{1}{5}+\dfrac{1}{4}\right)=0\)
\(\Leftrightarrow x-2020=0\Leftrightarrow x=2020\)
Vậy x = 2020
Kết quả là 3712570597955237990400
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