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\((2,5\cdot x+2017)\cdot2018=(7,5+2017)\cdot2018\)
\(\Rightarrow(2,5\cdot x+2017)\cdot2018=4085441\)
\(\Rightarrow2,5\cdot x+2017=2024,5\)
\(\Rightarrow2,5x=7,5\)
\(\Rightarrow x=7,5:2,5=3\)
\(3\frac{1}{5}+\frac{2}{5}\left[x+\frac{1}{3}\right]=\frac{21}{5}\)
\(\Rightarrow\frac{16}{5}+\frac{2}{5}\left[x+\frac{1}{3}\right]=\frac{21}{5}\)
\(\Rightarrow\frac{2}{5}\left[x+\frac{1}{3}\right]=\frac{21}{5}-\frac{16}{5}\)
\(\Rightarrow\frac{2}{5}\left[x+\frac{1}{3}\right]=1\)
\(\Rightarrow x+\frac{1}{3}=\frac{5}{2}\)
\(\Rightarrow x=\frac{13}{6}\)
a, ( x - 21 x 13 ) : 11 = 39 Tich mk cau b) ti nua mk lam cho gio phai di hoc them rui
x - 273 = 39 x 11
x - 273 = 429
x = 429 + 273
x = 702
a, ( x - 21 x 13 ) : 11 = 39 b, ( x - 21 ) x 13 : 11 = 39
( x - 21 x 13 ) = 39 x 11 ( x - 21 ) x 13 = 39 x 11
( x - 21 x 13 ) = 429 ( x - 21) x 13 = 429
x - 273 = 429 ( x - 21 ) = 429 : 13
x = 429 + 273 ( x - 21 ) = 33
x = 702 x = 33 + 21
x = 54
Ta có: \(\frac{x-2019}{2018}+\frac{x-2018}{2017}=\frac{x-2017}{2016}+\frac{x-2016}{2015}\)
\(\Leftrightarrow\left(\frac{x-2019}{2018}+1\right)+\left(\frac{x-2018}{2017}+1\right)=\left(\frac{x-2017}{2016}+1\right)+\left(\frac{x-2016}{2015}+1\right)\)
\(\Leftrightarrow\frac{x-1}{2018}+\frac{x-1}{2017}=\frac{x-1}{2016}+\frac{x-1}{2015}\)
\(\Leftrightarrow\frac{x-1}{2018}+\frac{x-1}{2017}-\frac{x-1}{2016}-\frac{x-1}{2015}=0\)
\(\Leftrightarrow\left(x-1\right)\left(\frac{1}{2018}+\frac{1}{2017}-\frac{1}{2016}-\frac{1}{2015}\right)=0\)
\(\Leftrightarrow x-1=0\)( vì \(\frac{1}{2018}+\frac{1}{2017}-\frac{1}{2016}-\frac{1}{2015}\ne0\))
\(\Leftrightarrow x=1\)
Vạy x=1
Nhầm,phần a mình sai rồi.Bây giờ mới đúng
53 x 39 + 47 x 39 - 53 x 21 - 47 x 21
=(53 + 47)x39 -(53 + 47) x21
=100 x 39 -100 x 21
=(39-21)x100
=18x100
=1800
Ta có : A =\(\frac{2017}{2018}\)x \(\frac{7}{8}\)+ \(\frac{2017}{2018}\)x \(\frac{3}{8}\)- \(\frac{2017}{2018}\)x \(\frac{1}{4}\)
= \(\frac{2017}{2018}\) x ( \(\frac{7}{8}+\frac{3}{8}-\frac{1}{4}\))
= \(\frac{2017}{2018}\)x 1
=\(\frac{2017}{2018}\)
Vậy A= : \(\frac{2017}{2018}\)
Bài giải
\(A=\frac{2017}{2018}\text{ x }\frac{7}{8}+\frac{2017}{2018}\text{ x }\frac{3}{8}-\frac{2017}{2018}\text{ x }\frac{1}{4}\)
\(A=\frac{2017}{2018}\text{ x }\frac{1}{4}\left(\frac{7}{2}+\frac{3}{2}-1\right)=\frac{2017}{2018}\text{ x }\frac{1}{4}\text{ x }4==\frac{2017}{2018}\text{ x }1=\frac{2017}{2018}\)
a) ( x -21 * 13) : 11 = 39 => x - 21*13 = 39 * 11 => x - 273 = 429 => x= 429 + 273 => x= 702 b) ( x - 21) * 13 : 11 = 39 => (x-21)*13=39:11 => (x-21)*13=429 => x-21=429:13 => x-21=33 => x=33+21 => x=54
câu c để mk suy nghĩ sau nhk