2009:[71:x]=2009
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a)4800 : ( X x 16 ) = 25
X x 16 = 4800 : 25
X x 16 = 192
X = 192 : 16
X = 12
b)2009 : ( 71 : x ) = 2009
71 : x = 2009 : 2009
71 : x = 1
x = 71 : 1
x = 71
Hok tốt
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a) \(437\times136-437\times125\)
\(=437\times\left(136-125\right)\)
\(=437\times11\)
\(=4807\)
b) \(2009\times71+29\times2009\)
\(=2009\times\left(71+29\right)\)
\(=2009\times100\)
\(=200900\)
a) 437 x 136 - 437 x 125
= 437 x (136 - 125 )
= 437 x 11
= 4807
b) 2009 x 71 + 29 x 2009
= 2009 x ( 71 + 29 )
= 2009 x 100
= 200900
![](https://rs.olm.vn/images/avt/0.png?1311)
\(a,4800:\left(x\times16\right)=25\)
\(x\times16=4800:25\)
\(x\times16=192\)
\(x=192:16\)
\(x=12\)
\(b,2009:\left(71:x\right)=2009\)
\(71:x=2009:2009\)
\(71:x=1\)
\(x=71\)
a,4800[x nhân 16]=25 b,2009:[71:x]=2009
x nhân 16=4800:25 71:x=2009:2009
x nhân 16=192 71:x=1
x=192:16 x=71:1
x=12 x=71
![](https://rs.olm.vn/images/avt/0.png?1311)
![](https://rs.olm.vn/images/avt/0.png?1311)
Bài 1 :Chiều dài khu vườn đó là:
468 : 18 = 26 ( m )
Đáp số: 26 m
Bài 2:
a) 48 : ( X x 16 ) = 25
=> X x 16 = 48 : 25
=> X x 16 = 1,92
=> X = 1,92 : 16
=> X = 0,12
b) 2009 : ( 71 : x ) = 2009
=> 71 : x = 2009 : 2009
=> 71 : x = 1
=> x = 71 : 1
=> x = 71
Bài 1 :Chiều dài khu vườn đó là:
468 : 18 = 26 ( m )
Đáp số: 26 m
Bài 2: a) 48 :
( X x 16 ) = 25
=> X x 16 = 48 : 25
=> X x 16 = 1,92
=> X = 1,92 : 16
=> X = 0,12
b) 2009 : ( 71 : x ) = 2009
=> 71 : x = 2009 : 2009
=> 71 : x = 1
=> x = 71 : 1
=> x = 71
![](https://rs.olm.vn/images/avt/0.png?1311)
![](https://rs.olm.vn/images/avt/0.png?1311)
![](https://rs.olm.vn/images/avt/0.png?1311)
\(\dfrac{\left(2009-x\right)^2+\left(2009-x\right)\left(x-2010\right)+\left(x-2010\right)^2}{\left(2009-x\right)^2-\left(2009-x\right)\left(x-2010\right)+\left(x-2010\right)^2}=\dfrac{19}{49}\left(1\right)\)
\(Đkxđ:x\ne2009;x\ne2010\)
Đặt \(t=x-2010\left(t\ne0\right)\)
\(\Rightarrow2009-x=-\left(t+1\right)\)
\(\left(1\right)\Leftrightarrow\dfrac{\left(t+1\right)^2-\left(t+1\right)t+t^2}{\left(t+1\right)^2+\left(t+1\right)t+t^2}=\dfrac{19}{49}\)
\(\Leftrightarrow\dfrac{t^2+2t+1-t^2-t+t^2}{t^2+2t+1+t^2+t+t^2}=\dfrac{19}{49}\)
\(\Leftrightarrow\dfrac{t^2+t+1}{3t^2+3t+1}=\dfrac{19}{49}\)
\(\Leftrightarrow49t^2+49t+49=57t^2+57t+19\)
\(\Leftrightarrow8t^2+8t-30=0\)
\(\Leftrightarrow4t^2+4t-15=0\)
\(\Leftrightarrow\left(4t^2+4t+1\right)-16=0\)
\(\Leftrightarrow\left(2t+1\right)^2=16=4^2\)
\(\Leftrightarrow\left[{}\begin{matrix}2t+1=4\\2t+1=-4\end{matrix}\right.\)
\(\Leftrightarrow\left[{}\begin{matrix}t=\dfrac{3}{2}\\t=-\dfrac{5}{2}\end{matrix}\right.\) \(\Leftrightarrow\left[{}\begin{matrix}x-2010=\dfrac{3}{2}\\x-2010=-\dfrac{5}{2}\end{matrix}\right.\) \(\Leftrightarrow\left[{}\begin{matrix}x=\dfrac{4023}{2}\\x=\dfrac{4015}{2}\end{matrix}\right.\)
2009 : ( 71 :x) = 2009
71 : x = 2009 : 2009
71 : x = 1
x = 71 : 1
x = 71