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5 tháng 7 2017

\(\dfrac{x-241}{17}+\dfrac{x-220}{19}+\dfrac{x-195}{21}+\dfrac{x-166}{23}=10\)

\(\Rightarrow\dfrac{x-241}{17}-1+\dfrac{x-220}{19}-2+\dfrac{x-195}{21}-3+\dfrac{x-166}{23}-4=0\)

\(\Rightarrow\dfrac{x-258}{17}+\dfrac{x-258}{19}+\dfrac{x-258}{21}+\dfrac{x-258}{23}=0\)

\(\Rightarrow\left(x-258\right)\left(\dfrac{1}{17}+\dfrac{1}{19}+\dfrac{1}{21}+\dfrac{1}{23}\right)=0\)

\(\dfrac{1}{17}+\dfrac{1}{19}+\dfrac{1}{21}+\dfrac{1}{23}\ne0\)

\(\Rightarrow x-258=0\Rightarrow x=258\)

Vậy x = 258

14 tháng 11 2018

x−24117+x−22019+x−19521+x−16623=10x−24117+x−22019+x−19521+x−16623=10

⇒x−24117−1+x−22019−2+x−19521−3+x−16623−4=0⇒x−24117−1+x−22019−2+x−19521−3+x−16623−4=0

⇒x−25817+x−25819+x−25821+x−25823=0⇒x−25817+x−25819+x−25821+x−25823=0

⇒(x−258)(117+119+121+123)=0⇒(x−258)(117+119+121+123)=0

117+119+121+123≠0117+119+121+123≠0

⇒x−258=0⇒x=258

22 tháng 2 2017

Giải:

\(\frac{x-241}{17}+\frac{x-220}{19}+\frac{x-195}{21}+\frac{x-166}{23}=10\)

\(\Rightarrow\left(\frac{x-241}{17}-1\right)+\left(\frac{x-220}{19}-2\right)+\left(\frac{x-195}{21}-3\right)+\left(\frac{x-166}{23}-4\right)\)

\(=10-1-2-3-4=0\)

\(\Rightarrow\frac{x-258}{17}+\frac{x-258}{19}+\frac{x-258}{21}+\frac{x-258}{23}=0\)

\(\Rightarrow\left(x-258\right)\left(\frac{1}{17}+\frac{1}{19}+\frac{1}{21}+\frac{1}{23}\right)=0\)

\(\Rightarrow x-258=0\)

\(\Leftrightarrow x=258\)

22 tháng 2 2017

\(\frac{\text{x−241}}{17}+\frac{220}{19}+\frac{x−195}{21}+\frac{x−166}{23}=10\)

\(\Rightarrow\left[\frac{\left(x-241\right)}{17-1}\right]+\left[\frac{\left(x-220\right)}{19-2}\right]+\left[\frac{\left(x-195\right)}{21-3}\right]+\left[\frac{\left(x-166\right)}{23-4}\right]=10-1-2-3-4\)

\(\left(\text{Cộng 2 vế cho -1 - 2 - 3 - 4}\right)\)

\(\Rightarrow\frac{\left(x-258\right)}{17}+\frac{\left(x-258\right)}{19}+\frac{\left(x-258\right)}{21}+\frac{\left(x-258\right)}{23}=0\)

\(\Rightarrow\left(x-258\right).\left(\frac{1}{17}+\frac{1}{19}+\frac{1}{21}+\frac{1}{23}\right)=0\)

\(\Rightarrow x-258=0\Rightarrow x=258\)

14 tháng 6 2015

=> \(\frac{x-241}{17}-1+\frac{x-220}{19}-2+\frac{x-195}{21}-3+\frac{x-170}{22}-4=0\)

<=> \(\left(\frac{x-241}{17}-\frac{17}{17}\right)+\left(\frac{x-220}{19}-\frac{38}{19}\right)+\left(\frac{x-195}{21}-\frac{63}{21}\right)+\left(\frac{x-170}{22}-\frac{88}{22}\right)=0\)

<=> \(\frac{x-258}{17}+\frac{x-258}{19}+\frac{x-258}{21}+\frac{x-258}{22}=0\)

<=> \(\left(x-258\right).\left(\frac{1}{17}+\frac{1}{19}+\frac{1}{21}+\frac{1}{22}\right)=0\)

<=> x - 258 = 0  do \(\left(\frac{1}{17}+\frac{1}{19}+\frac{1}{21}+\frac{1}{22}\right)\ne0\)

=> x = 258

10=1+2+3+4

X=241+17x1=258

X=220+19x2=258

X=195+21x3=258

X=170+22x4=258.

a: \(\dfrac{2032-x}{25}+\dfrac{2053-x}{23}+\dfrac{2070-x}{21}+\dfrac{2083-x}{19}-10=0\)

\(\Leftrightarrow\left(\dfrac{2032-x}{25}-1\right)+\left(\dfrac{2053-x}{23}-2\right)+\left(\dfrac{2070-x}{21}-3\right)+\left(\dfrac{2083-x}{19}-4\right)=0\)

=>2007-x=0

hay x=2007

b: \(\Leftrightarrow x+\left(1+1+1+1+1+1+1\right)+\left(\dfrac{1}{12}+\dfrac{1}{20}+\dfrac{1}{30}+\dfrac{1}{42}+\dfrac{1}{56}+\dfrac{1}{72}+\dfrac{1}{90}\right)=0\)

\(\Leftrightarrow x+7+\left(\dfrac{1}{3}-\dfrac{1}{4}+\dfrac{1}{4}-\dfrac{1}{5}+...+\dfrac{1}{9}-\dfrac{1}{10}\right)=0\)

=>x+7+1/3-1/10=0

hay x=-217/30

30 tháng 6 2017

\(\dfrac{148-x}{25}+\dfrac{169-x}{23}+\dfrac{186-x}{21}+\dfrac{199-x}{19}=10\)

\(\Leftrightarrow\left(\dfrac{148-x}{25}-1\right)+\left(\dfrac{169-x}{23}-2\right)+\left(\dfrac{186-x}{21}-3\right)+\left(\dfrac{199-x}{19}-4\right)=0\)

\(\Leftrightarrow\dfrac{123-x}{25}+\dfrac{123-x}{23}+\dfrac{123-x}{21}+\dfrac{123-x}{19}=0\)

\(\Leftrightarrow\left(123-x\right)\left(\dfrac{1}{25}+\dfrac{1}{23}+\dfrac{1}{21}+\dfrac{1}{19}\right)=0\)

\(\Leftrightarrow123-x=0\Leftrightarrow x=123\)

Vậy x = 123

30 tháng 6 2017

thanks you

11 tháng 7 2017

a) Ta có: \(\dfrac{x}{y}=\dfrac{17}{3}\Rightarrow\dfrac{x}{17}=\dfrac{y}{3}\) và x + y = 60

Áp dụng tính chất của dãy tỉ số bằng nhau:

\(\dfrac{x}{17}=\dfrac{y}{3}=\dfrac{x+y}{17+3}=\dfrac{60}{20}=3\)

\(\dfrac{x}{17}=3\Rightarrow x=17.3=51\)

\(\dfrac{y}{3}=3\Rightarrow y=3.3=9\)

Vậy x = 51; y = 9

b) Ta có: \(\dfrac{x}{19}=\dfrac{y}{21}\Rightarrow\dfrac{2x}{38}=\dfrac{y}{21}\) và 2x - y = 34

Áp dụng tính chất của dãy tỉ số bằng nhau:

\(\dfrac{2x}{38}=\dfrac{y}{21}=\dfrac{2x-y}{38-21}=\dfrac{34}{17}=2\)

\(\dfrac{x}{19}=2\Rightarrow x=2.19=38\)

\(\dfrac{y}{21}=2\Rightarrow y=21.2=42\)

Vậy x = 38; y = 42.

11 tháng 7 2017

Ta có : \(\dfrac{x}{y}\) = \(\dfrac{17}{3}\) \(\Leftrightarrow\) \(\dfrac{x}{17}\) = \(\dfrac{y}{3}\)\(x+y\) \(=60\)

\(\text{Áp dụng tính chất của dãy tỉ số bằng nhau , ta được : }\)

\(\dfrac{x}{17}\) = \(\dfrac{y}{3}\) = \(\dfrac{x+y}{17+3}\) = \(\dfrac{60}{20}\) = \(3\)

\(+\)) \(\dfrac{x}{17}\) \(=\)\(3\) \(\Rightarrow\) \(x=51\)

+ ) \(\dfrac{y}{3}\) \(=3\) \(\Rightarrow\) \(y=9\)

Vậy \(x=51\) ; \(y=9\)

Ta có : \(\dfrac{x}{19}\) = \(\dfrac{y}{21}\) \(\Leftrightarrow\) \(\dfrac{2x}{38}\) \(=\) \(\dfrac{y}{21}\)\(2x-y=34\)

\(\text{Áp dụng tính chất của dãy tỉ số bằng nhau , ta được : }\)

\(\dfrac{2x}{38}\)\(=\) \(\dfrac{y}{21}\) = \(\dfrac{2x-y}{38-21}\) \(=\) \(\dfrac{34}{17}\) \(=\) \(2\)

+ ) \(\dfrac{2x}{38}\) = \(\dfrac{x}{19}\) \(=\) \(2\) \(\Rightarrow\) \(x=38\)

+ ) \(\dfrac{y}{21}\) = 2 \(\Rightarrow\) \(x=42\)

Vậy \(x=38\) ; \(x=42\)

25 tháng 12 2017

Tính 1 câu thoy nhé !

\(\dfrac{3}{7}.19\dfrac{1}{3}-\dfrac{3}{7}.33\dfrac{1}{3}\)

= \(\dfrac{3}{7}.\left(19\dfrac{1}{3}-33\dfrac{1}{3}\right)\)

=\(\dfrac{3}{7}.-14=-6\)